Just got a set of guyker tuners for a cheap 90's Squier strat (that plays as well as ane American Fender Strat I've ever played.). I have the same issue of cutting strings (the .009 string specifically). I never thought about sanding the top of the locking screw. I'll try that. Thanks. Otherwise I'm really not too mad at them for the price. The materials seem to be the standard metals they're all made of. Fit & finish seems to be where corners are cut. A little sanding & oiling should make them generally functional.