My experience with Thompson guns is limited to shooting them; I know diddly-squat about their internals.
However, I did find a thread where a fella mentioned that he had issues similar to what krcoachran described. One of the replies in that thread was from was from a member that had the issue in two guns and in both instances the culprit was a weak pawl spring: http://www.machinegunboards.com/foru...showtopic=4226
Regards,
Greg