My truck had the same issue. In my case the threaded shackle pin started turning itself out of the threaded bushing instead of just rotating back and forth. Mine was bad enough it ruined the shackle side plates as well as the threaded bushing and pin. Yours may have a similar problem. This may be hard to understand if you haven't disassembled a shackle but it should be clear if you start taking it apart. In any case, don't just try to squeeze it back in place. First figure out why it is doing that and fix it.
Chuck
