Tolerance issue, you mean some small kind of tweaking issue that is a bit off? I would think also since most of the time it shoots good, but not always...
And about fixing the problem, I bought it from ehobbyasia, and I myself am from Europe.
So, dunno if that is interesting.
Of course the most interesting thing is to find or bump against somebody that has a knowledge of this gun inside.
There is a "spring" (dont know the right term) behind the left handgrip that seems to do nothing...
its just there for no reason it seems, its behind the thing that moves when you cock the hammer or pull the trigger...
Can somebody with a ppk look behind the left handgrip for that piece and if it also sits there like it does on mine?