D.M. Procida 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.