Yeah, I got that. I might have to make a video to explain what I mean - basically, the mouse is very touchy when moving the pick from one pin to another, and if I move it at all to the left while setting a pin, it'll move over. It's a bit of a pain.
I do know that there's a repeating 'pattern', as you explained well. +rep for trying to solve the unsolvable, 'cos if that'd been my problem it'd be good and solved.