Hello, I'm installing this vise on a Roubo bench... the issue I'm having is that the wagon runs smoothly in the slot, until I fully tighten the "collar" on the outside...at that point it hangs up badly. I've tried shimming both the left and right side of the collar and no luck. Everything is fine until that final quarter turn to snug up the collar, and then the wagon won't move. Something is out of alignment, but I can't figure out what.... Any help would be appreciated! Thanks!!