I’m currently rebuilding several of my old, road bikes. The problem I ran into was with a Suntour Cyclone, rear derailleur on a Centurion twelve speed that is probably from the early eighties. I should have been paying more attention but in my usual haste to get the job done I pulled the rear derailleur without noticing how it was mounted. My problem now is that I am reassembling it won’t pivot from the point at which it attaches to the frame. Looking at my other bikes, it should pivot in two places. It may be that I lost a spacer but I haven’t been unable to find it. On another of my bikes the mounting bolt has a shoulder that keeps the bolt from tightening down too far. On a second bike there is a nut on the backside of the threaded frame mount that is tightened to attain the correct spacing. The bolt on this derailleur doesn’t protrude through the threaded frame mount so it obviously didn’t have a nut to secure it. The bolt does have a shoulder but the shoulder is short by a fraction of an inch of being able to give the derailleur room to flex. When the bolt is tightened down it pinches the derailleur and won’t allow it to pivot. There isn’t a lot of room for any extra spacers. I did find one standard washer but it doesn’t do anything to help keep it free to rotate. Any ideas would be appreciated.