I got this Harley Benton DC Junior a few years ago and it's been my main axe since.
Only issue is it has the worse tuning stability of any guitar I've owned, Not only going out of tune but getting it to correct pitch can be spotty in the first place.
Any ideas for replacement tuning machines? I've already replaced the nut with a graphtech one a while back and it only slightly helped when tuning up. I also don't mind drilling new screw holes if need be.
I forgot to mention, on the 3x3 Gibson style headstock, the string pull angle is not great on both your E strings, and to less extent the A and B and could be binding. Another thing that just popped in my head - I'm not familiar with that particular model, but if it's a bolt-on neck, make sure the neck is tight and not moving at all. Another place to check is the bridge and tail piece, I'm assuming it's a Tune-O-Matic style. Check if you're having binding issues at the saddles, and that the threaded inserts (bushings) in the body aren't loose - this happens on Gibsons and Epiphones as well. If that's the case, take the bridge and tail piece out and carefully wick in some super thin CA glue to help stiffen them up
Yeah, just double check that there's no wiggle there or in the neck to rule those out, no sense throwing money at tuners if it's not going to fix the problem.
And I have an Ibanez that's 3x3, but the string angle at the nut is much less pronounced on it versus the Gibson/Epiphone angle, along with a shallower headstock break angle. Not saying it's your issue, but binding can occur there, although you did say you swapped it for a graphtech which should eliminate that as a point of concern.
Shit I missed where you said glued neck, you'd know if it was loose. Derp! Just check the bushings and the bolt/threaded rod they ride on and make sure there's no wiggle room there, a loose or wallered out threaded bushing can affect tuning stability. Just making sure you check everything before throwing money at it.