Finally a topic, cleaning and polishing metal parts, on which I can
speak with some authority.  I spent over ten years running a jewelry
manufacturing business.  When I restored my first upright players I just
assumed that the metal parts should be cleaned and polished.  I never
regretted the time spent, especially when someone would say, "Where did
you get those new parts?"

Even if you are only going to restore one piano I would suggest you
build a buffer -- and I don't mean a fluffy pad on a hand-held drill.
Once you have a buffer in your shop you will find a thousand uses for
it.  Preferably your buffer should be double shafted.  It is quite
important that it have an RPM of 3400.  The slower speed is ineffectual
as a buffer; don't waste your time on a 1700 RPM motor.  The absolute
minimum size is 1/4 HP but frankly the bigger the better.  The easiest
way to obtain a double-shafted motor of adequate size is to buy one of
the foreign import grinders, remove the wheels, and add the buffing
accessories.  Those grinders are surprisingly inexpensive.  However, make
sure that the shaft size is something standard, i.e. 1/2" or 5/8", and
that the corundum wheels can be removed.

Your next step is to acquire buffing accessories.  Taper spindles are a
concept that is foreign to most folks outside of the jewelry industry.
What they do is to allow you to change buffs in a matter of seconds
without removing any nuts or other fasteners.  If you have a double-
shafted buffer, you will need a left and right threaded taper spindle of
the correct shaft size.  Next item is the buffs, and I like the 6"
unstitched lead-centered ones.  There are many different kinds of
buffing wheels, cotton, muslin, stitched, and unstitched, lead centered,
shellac centered, etc.  Buffing wheels are not that expensive, so I
would suggest that you buy a couple different styles to try out.

One important thing: DO NOT CROSS CONTAMINATE.  Use each buffing wheel
for one kind of buffing compound only.  Before starting the buffing
process, make sure the article is clean and degreased.  As to buffing
compounds, you can accomplish everything that needs to be done with only
two buffing compounds: bobbing compound and a final polish ZAM.  Bobbing
compound is quite aggressive so be careful.  Bobbing compound can leave
the work piece a little dirty, so clean up with mineral spirits or some
similar solvent before going to the final polish with ZAM.  ZAM is a
fine polish in a hard wax, so it doesn't leave much residue.  Avoid
jeweler's rouge; it is dirty and difficult to clean up.  If you need to
polish and leave a nice finish on small wood articles, I would suggest
HUT Wood Finish, which is also a buffer-applied product.

Sources:

    Tapered spindles, buffs and HUT wood finish from:
        HUT Products
        4502 HWY J
        Fulton, MO 65251
        800 684 9371

    Bobbing compound and ZAM: any jewelry supply house.  A good one is:
        Ebersole Lapidary Supply
        11417 W HIWAY 54
        Wichita, KS 67209-1298
        877 323 7765

Happy polishing,
Tom Hutchinson