The electric motors in pianos came in a variety of different models.
Many of the ones made for coin operated pianos can be reversed easily.
The Ampico and Duo-Art motors are much more difficult to reverse.

Usually you reverse the field windings.  Motors in many coin pianos
have two Bakelite nuts that connect to your electricity supply (110
vac).  There are usually two wires coming out of the motor that connect
to these two nuts.  They are your field windings.  Reverse these two
wires and the motor changes direction.  There are two more wires inside
that you don't see and you need not touch them.

Now one of the readers that is an electrical engineer can write an
article about AC motors.

Don Teach