As far as I recall, the aperture ring uses a small steel ball.

Focus overturning: somebody has been at this lens before and forgot a part or 2, 3......

Take of the lensmount (3 screws) and the rings below and see if you have any holes without a srew in it....
You probably will !

Best advice: get a lens with bad optic's for very cheap and use that as a donor.

Peter