Just a note here regarding phonograph motors and idler replacement.
Very often the rubber idler wheel in jukeboxes and home record changers
will become unusable, either because it has hardened or has developed
the familiar flat spot where it has sat against the motor shaft for
years.

Remember that in replacing the idler wheel, the only thing that matters
is that the wheel fits on the mechanism's shaft.  The actual outside
diameter of the idler wheel does not matter.  The speed will be the
same since the idler's job is not to determine speed, but is to
transfer the power of the motor to the inside of the turntable rim.
The outside edge of the idler wheel will _always_ turn at the same rate
no matter what size the wheel.

John D. Rutoskey