John wrote:

I'm restoring an old tape recorder. The capstan flywheel is very lightly
pitted. I'd like to polish this out.

Don't you stand a fair chance of unbalancing the flywheel in the
process?

What would be a suitable polish? Or if it's likely to be too hard for a
polish, could it perhaps be sanded first?

Normally I'd turn the capstan on a lathe to get rid of the pits.

It will need to be the very finest abrasive paper, because it needs to
have an extremely smooth surface.

P180 paper would probably do the job, leaving a finish smooth enough to
polish using a cotton mop on a polisher spindle using an abrasive stick
to dress the mop. However the chances are that in the process of sanding
and polishing that you will get the flywheel out of shape.

Capstan flywheel - or capstan spindle? The finish on the flywheel has no
functional consequence.

Not even where the belt makes contact with it? I imagine it must have
only a tiny effect, if any, but since the flywheel is meant to be smooth
and not pitted, it seems better to restire it to that condition.

Daniele