I have a Barley Crusher and mine was manufactured in a way that I can't set a consistent gap across the rollers. Either the rollers were not cut straight, or the body/frame of the mill isn't square.
When I set a consistent gap, the non-drive roller "pinches" every 180* of rotation and won't spin freely, and won't pull grain through the rollers. To get it to spin freely, I have to either loosen or tighten one side. This creates an inconsistent gap, but it does allow the non-driven roller to spin freely and doesn't seem to negatively impact my crush.
You may have the same issue with yours...