i own three and i guess i'm lucky i got nice ones (all from the bay.) first, is the blade centered? because if it is, the washers are probably ok. your problem is either the pivot itself (tight or contaminated) or the lock bar detent scratching the tang. if the blade pivots well enough on its own, there's no problem there. so look at the tang and lock bar insert. is the insert firm or loose? is the tang smooth and even? does the detent ball engage the hole each time? last, look at the tang concave. there's always a scratch on the part where the detent ball drops (some people think this is an early lock.) the ball should drop on the same spot each time.
the ti millie has a pretty simple mechanism and a poor opening might be a qc lemon. show it to a dealer.