I fixed this on  my 82 years ago.  I remember that a small white drive gear
had a radial split, allowing the shaft to turn without enough grab to turn
the gear. There was a small hub on the gear and I found a small internal
star washer that fit over the hub. It created enough tension with the help
of some super glue to do the job.  I seem to remember something on the list
about someone who had replacement gears to fix this problem.

Bob