One thing that I haven't seen mentioned either here or in your previous thread describing your problem is that a likely cause could be as simple as a Bent Moon Clip. Yeah, I do have a bit of experience with what can happen if a moon clip gets bent having experienced what happens with my 610-3 and 625-8. What I would suggest is that you take a simple 1 dollar electric engraver and number every on of your moon clips. That was if you problem ever re-occurs you can note that the moon clip that was in used may be bent. BTW with a good flat surface it can be somewhat easy to spot the "leg" that is bent and then straighten in with some pliers.