Hi,  Unfortunately when I looked for my Ampico diagrams I couldn't find
them (I must have given them to the person that purchased my Ampico),
but logic tells us that the problem is not with the rewind lever but the
repeat control system.

The rewind is competing with the repeat.  In the drawer the same
pneumatic box (a rather odd shaped one) controls both reroll and play.
If you trace the rewind symbol back to the roots you will find that it
has a leak of some kind or the control valve is faulty.  If you want
to verify this you can disconnect the repeat pneumatic from the supply
tube and see what happens when you reach rewind.  Note: You can also
verify this way that the repeat valve is stuck on as it will have
vacuum through that tube constantly.

Or, the inputs could simply be crossed in which case you would see
that the vacuum comes only when the repeat is supposed to be
playing -- in which case all you have to do is switch the tubing.

Eli Shahar