A few years ago I bought a new Strat that sounded amazing in the store. However, I made a mistake. I didn't test the Tremolo before I brought it home. I know that seems stupid, but I don't use the Trem in my natural playing. Given how aggressively I bend the strings, I never thought a brand new guitar which stayed perfectly in tune while I tried it out, would have something seriously wrong with it. But I was wrong. Anyway... First I bring the guitar back to the store. The guitar tech can't fix it. I'm then referred to Fender's 'expert' repairman for the state. He can't fix it either. I'm then given the option of giving it back to Fender and being sent a new one. But this guitar sounded so special, I decided to keep it and just never use the Trem. Amazingly, a few days ago I figured out how to fix it. Or to put it more accurately, I figured out - How to figure out what was wrong. Here is what I did. First, one by one, I detuned the strings starting with the low E. By detune, I mean I loosened them to the point they could provide no resistance what-so-ever. I then brought the remaining 5 strings back to pitch. Next, I abused the whammy bar for all it was worth. I wanted to see how far out of tune the other strings were going. What showed up kind of blew me away, some of the strings always returned to tune. But others might be sharp or flat. When I loosened the G and the B strings, the remaining strings returned to tune much better. So I detuned the G and B together, once again, big improvement. This told me was where my problem was and that there was nothing seriously wrong with the guitar such as improperly drilled posts, which is a problem that could never be fixed. If some of the strings always return to tune, the guitar is in balance and the Trem mechanism is working properly. This narrows the potential problem spots to saddles, nut, string trees or tuners. Testing the string tree is pretty easy, just take the strings out of it and see if your Trem now stays in tune. Testing the tuners is also pretty easy, stretch the crap out of your string. If it stays in tune while you are increasing and decreasing pressure upon it, odds are the tuner is holding fast against the Trem's action as well. This leaves the nut. I applied a little high grit sandpaper to the G and B string groves, angling downward toward the tuners and that fixed the problem. The fact that the strings were binding in multiple places had befuddled two expert repairmen because they could not get a consistent failure result. However, by eliminating strings, one by one, I was able to correctly target the problem spots. Using nut lube or pencil graphite really shouldn't be beyond anyone. Installing new tuners or a string tree, assuming you buy the correct parts also shouldn't be that difficult. Installing a new nut might be a little more challenging and you may want to pay for that. But once you know where the problem lies, it's pretty easy to figure out what to do about it.