Shaft Binding On V10-p Maximat

[Wheresmywrench?]

When I tighten up the bearing retaining ring behind the lathe chuck it causes the shaft to bind. If I loosen them off a little it rotates freely. But then I get side play in the shaft which results in defection. I'm thinking of making some brass shims to see if I can get it into a happy place. I think the reason for the problem is I had to rob gear box form a older V10-P but I think there was a difference in the thickness of the gear box which accounts for the problem I am having. Any ideas??