The likely damage was a a limit-of-travel stop broken off the inner end of the pivot shaft.
Following crashing my Zoom I encountered the same symptoms, i.e. rear arm that would lift (when the drone was throttled up etc.) and the drone would occasionally get the shakes in mid air. Repair in this case probably means replacing the arm, the break surface is almost certainly contaminated with grease so I doubt gluing the stop back in place is feasible even if you can find the broken of stop, (Mine was stuck, by grease, in the circunferential groove, in the pivot's bore, in which the stop slides.)
I replaced the arm, it came with a motor so it was more or less a straight swap.