I just bought a used Loomis FR with a Tremol-no installed. Damn fine instrument, BUT the fucking bridge will not return true (just set it up with brand-spankin' new 10-46+60s). Any sort of divebomb or pull-back manoover causes it to return to something a half-step sharp or flat, with the baseplate of the trem visibly off of parallel (this confused me when I was trying to set it up for the first time, let me tell you).
Now, I've got all the tremol-no knobs loosened, so I know that's not the problem. Could old springs cause this?
EDIT: Looking at it now, I have a suspicion the tremol-no could use some good old WD-40. Is there any reason I shouldn't do that?
Pop off the back half of the Tremol-no (the half that attaches to the block), leaving only the claw side in place. If the problem goes away, then the problem is claw screw alignment.