You can change the stripped gears.  I have never had to change more
than one gear, as the gears that are good are usually made of something
other than plastic.

I had Bob Streicher make me a whole bunch of gears.  I have both types
of the gears that go bad.  Bob makes precision Kimball cluster gears
out of brass.  I drill out the rivets to open the gear box, change
the gears and replace the rivets.  I've worked on four transmissions
successfully.  The brass gears are only slightly louder than the
plastic gears.  I rely heavily on Bob for so much and he always comes
through.

You can email me and I will sell you the gears, or give Bob Streicher
a call at (570) 559-7403.

Bill Maguire