I've had few ZT's and I've been happy with them except for the 350. I had the same problems: blade offcenter (my suspicion is the linerlock pushing it too much(?)) and the blade hitting the backspacer.
Same here, of all my ZTs, the 0350 is the only one the just won't center. It's been pointed out before, and I believe mine has the same problem, the blade is not actually "true" or strait/flat. I have managed to get it from rubbing, but that's it.
It's a user, so I don't really mind. If I would have known this though, I might have picked a 030x as my first ZT.