With a bean-counters brilliance the factory decided to downgrade the locking stud system they've been using since 1985 on their Edge and Lo Pro equipped guitars to the cheaper non locking stud the cheaper Korean models have always had. This is the best mod I could come up with to add the locking studs to the Edge Pro equipped guitars, short of pulling the stud inserts and putting a set of Lo Pro inserts in, which is unnecessary with this set screw mod.
Why do you want locking studs? A stud that's allowed to move will not always return to the exact spot causing tuning to be slightly out after whammy use. Any movement in a double locking system is not conducive to stability. A nut that's walking whacks tuning out a specific way, pull-up it returns flat, dive it returns sharp, very peculiar and easy to diagnose. Very erratic return is usually from an unstable pivot point. The first thing I check on used guitars that have horrid return is the stud inserts [the stud's anchors that are press fit into the wood] because when they oval the wood and get loose they will never return to the same spot between dive and pull-up stresses. This causes super erratic swings in pitch with no really stable or even predictable return, It's the unpredictability that points directly to an unstable pivot. Loose studs work on the same principle, even though it effects tuning to a smaller degree, it does have an effect. Nothing beats a stable pivot point to give you absolutely predictable trem return. Ironically the loosening of these inserts in older guitars is largely attributed to non locked studs that have wiggled back and forth enough it's caused the insert to oval the wood [although I have had a New Old Stock LNG Jem with maybe an hour of total play time that had significantly oval'd inserts just from sitting in a case for 15 years. Basswood is a soft wood and susceptible]. After many years I have concluded loose anchors is a function of the wood itself. Basswood is soft and with over 100 pounds of pressure on it, most of the time the anchor will impress into it. I discovered that anchors set high with the top of the anchor at the top of the rout almost never impress, and high set anchors where the top of the anchor slightly protrudes above the wood, never impress. I believe it's because the sealer and paint soak into the wood and make it so much harder than unsaturated basswood that they cannot impress into this harder material.
How this works -
On the left is the old 2LE2B locking studs [note the extended set screw in the center of the stud] and 2LE2A inserts that have a solid base. On the right is the new non locking EP studs and the open base inserts. Because there's no set screw to lock there's no point in spending the pennies to machine the base into the insert.
The base of the EP insert needs to be securely plugged so the set screw in the stud can lock against it. On the left is the insert with a socket head set screw to plug the base, and on the right is the set assembled with either a locking or non locking stud. [Editors note - I originally wrote this thinking that *locking* the non locking studs to just the set screw plug would be a great cheap fix, $1, you're done. $1, and about 15 minutes of work every time you want to make even a slight action adjustment. Spend the extra ching and buy locking studs, $25 now saves a buttload of aggravation later.]
This shows how either would lock together but I left a little room between them for the shot. The locking stud on the left you would use the set screw in the stud to lock against the 6mm set screw that adds a base to the EP insert. The non locking stud on the right will lock itself against the 6mm set screw, the set screw would have to be adjusted for the correct action height and then the stud tightened against it for the lock. It does work extremely well, it's a PITA to adjust. Not recommended. Opt for the locking studs.
For you DIYers the specific part is - 8M, 1.25 pitch, socket head set screw. A 4mm length would be optimal for flexibility but 6mm is the shortest available and will allow 2mm action at the last fret with .5mm neck relief. A neck shim [which all Ibanez need to begin with to get ample pull-up range on the bridge] will be needed to get sick low 1mm action some of you like, or, the 6mm set screws can be easily ground down to 4mm. I grind every one I use down to 3-4mm thick.
A quick note about studs. The best studs are the original redesigned batch Gotoh cut when the pinched stud problem was corrected [see this page]. They have a very open U profile to the groove the knife edges sit in. There has been another batch of locking studs cut since this batch, and the profile is no where near as good as the original batch. The original batch I call Super Studs. The concurrent batch is still much better than the pinched studs of previous years, but they are V shaped in the groove and not U shaped. Unfortunately the batches are mixed and the Super Studs are cherry picked to use and sell for the stud mod. I sell the more V grooved studs as replacement studs for the 15+ years of pinched stud guitars and they do perform much better than those original studs. Ironically, the non locking EP studs have the same profile as the Super Studs, unfortunately, they just don't lock.
For optimal results the knife edges of the EP trem will need attention. The flat and curved sides are far too wide for free trem return, and the curved sides are actually the fattest that have ever been put into an Ibanez trem. See this page for directions, but be forewarned, don't screw it up!!
What To Do
Remove the bridge as detailed here. [Before you put it back in!! Check the profile of the knife edges themselves described here as knife edges binding on the studs is another cause of specific return problems, specifically, dive it returns in tune but pull up and it returns sharp.] Remove the non locking studs from the body. With a 4mm Allen wrench thread the ground socket head set screws down into the stud inserts [If the base of the set screw is not perfectly flat or you have them at an angle you will cross thread them. Any sign it's cross threading back them out and begin again, keep them as perpendicular to the insert as possible. Typically I will put the set screw in the top of the hole with the allen wrench on it and then screw counterclockwise until I'm sure it's flat and won't cross thread when I screw it down]. Keep downward pressure on these set screws as they're ground thin enough that most of the Allen hole is gone, just enough left to get the Allen to grip and spin it down, but not so much it will be easy to find the hole again if you slip out with the wrench. Screw them all the way down until they just make contact with the wood, then back them back out a hair by spinning the wrench 180 degrees. This will keep the pressure of locking the threads of the locking stud from pushing the set screw into the wood, possibly raising the insert a hair. With both set screws in take your new 2LE2B locking studs and screw them in. Use your fingers or the 4mm Allen for speed. Reinstall the trem.
You will have to do a basic setup after installing the mod as the V in every batch of studs is cut to a different depth which means you will have to adjust the trem angle. Of course you will need to set the action height also. Once the setup is finish and the *final* action adjustment has been done, use a 1.5mm Allen wrench and tighten the set screw inside the stud. Once they are tight you will need to use the 4mm Allen again in the stud to take all the remaining slop out of the threads. Usually no more than 1/8 of a turn but it depends on how tight you got the studs set screws to begin with and just how much slop there is between the threads, some are fairly snug, some are really sloppy. You're not trying to break the set screw under the stud or spin it hard enough to spin the insert [that anchor the stud is in], but you do want to take the slop out of the threads effectively locking the stud.
One last step to maximize performance is to lube the pivot point. I've tried greases and lubes and nothing had a really positive effect until Gary Brawer turned me onto what he's been using in JS's guitars, Chapstick Lip Balm [originally a tip to Gary from Tom Anderson as what he used for nut lube]. Back out the stud 180 degrees and dab a ball of Chapstick in the groove directly opposite the knife edge so that when you spin it 180 degrees back it will be on the knife. Whammy a bit to work it around and then test again, you should find improvement in the tuning return.
Public Service Announcement - Remember to always fine tune after releasing the bar from a whammy dive. This is what I'd call your *stable neutral*. When you bend strings you're pulling the bridge slightly forward so this is the natural return position of the bridge while normally playing. No trem will be 1000% on return from a pull-up but it should be so close you'll never know unless looking at a tuner, and then still barely off. Once you dive the bar it will always return to perfect tune again [as long as the guitar is in good setup, maintenance, and the strings properly stretched] which is why you always fine tune in the exact same spot every time, with the bar returning to neutral from a dive.