Hi Richard,  In all likelihood the cylinder shaft has become frozen in
place due to a buildup of dried grease and or oxidation or corrosion
after having sat unused for many years.  (You didn't mention a spring,
that should be on the right side of the cylinder which is designed to
drive the cylinder back to the left after the snail has completed its
cycle.  If you don't have that spring, let me know, I can provide you
with one if need be.)

I'm sure you'll get multiple replies, but here are my suggestions:

First, (before trying the items below) having left the penetrating
oil to soak in, on the cylinder shaft, for a few hours, try moving the
cylinder again back and forth, left and right on its central axle while
also trying to turn the cylinder slightly forward and back again.
Hopefully that will break up the adhesions and allow you to remove the
cylinder from the central shaft.

If that doesn't work, you can put a cap (protective cover) over the
portion of the cylinder shaft sticking out on the right side, (wrap
the cylinder with a piece of terry cloth towel -- and then while
holding the cylinder securely), firmly tap the capped end of the
cylinder shaft from right to left to help break the adhesions and get
the cylinder off the shaft.

If you are successful in removing the cylinder from the shaft, you'll
need to clean the shaft very well, to remove any debris, and also rub
it down with some very fine steel wool.  (The shaft and associated gears
can be put into your ultrasonic cleaner, _but not the cylinder!_)  Then
you'll need to clean it (gently ream out the cylinder shaft holes in
both ends of the cylinder such that the cylinder will slide easily back
and forth on the shaft.)

If the above and the penetrating oil hasn't worked try a few drops
(_not_ a spray) of WD-40 applied to the cylinder shaft where it enters
and leaves the cylinder.  Let it sit for a few minutes and again try to
move the cylinder to the right with a little leverage/wedge between the
cylinder and the cylinder drive gear; driving the cylinder to the right
should be okay.

If WD-40 doesn't do the trick, try a couple of drops (judiciously
applied) of Goof Off.  It's strong stuff and will dissolve any old
dried grease.  Just don't overdo it.  Goof-Off, if used in excess can
also dissolve the resin inside and you don't want that to happen.
(Note that the pins are set quite a distance from the central core near
the shaft and the Goof-Off isn't likely to get anywhere near the pins.)

Hopefully, the above should resolve your problem(s).  Please feel free
to call me if you have any questions or concerns.  Also let me know if
you need someone to clean and polish the cylinder, and/or if the
musical comb needs to be re-dampered.

Most sincerely,

Don Caine - Proprietor, The Music Box Repair Center Unlimited
Lomita, California
tel.: 1-310-534-1557
http://www.musicboxrepaircenter.com/