Mamiya Universal/Super 23 50mm lens help needed.

Hey guys,
I have mamiya super 23 and universal i got one 50mm 6.3 lens in used condition and there is a problem with mounting when i mount it the chrome bar gets stuck behind the rangefinder stick in body. recently i got a new lens in box that does not have this problem.....anyone has simmilar problems?
i wanted to sell the used one but without repair it is hard o mount it so that the chrome bar does not get stuck.

Is the mount on the lens bent?
Check it with a straightedge or metal ruler held against the ears of the mount.