Tumbler for small parts. It's about a thousand times easier than other methods and other than picking out the media afterwards relatively painless.

I don't use an ultrasonic cleaner on metal parts, but many do. I just soak them in a degreaser and then rinse and dry before going in the tumbler (helps keep the tumbler media from getting gunked up).

For grained ball guides and ramps I use an abrasive ball (see link below). Use coarse for heavy ball marks and medium to finish up. You can also get smaller ones for doing the inside of metal ramps. Scotch pad would also work for this, but a lot more work.

http://www.harborfreight.com/4-80-grit-coarse-grade-abrasive-ball-61182.html

Lockdown receiver I clean with a degreaser and then sand-blast. You could instead use a scotch pad and/or steel wool.

I have never come up with a method for the lockdown bar that replicates the original finish, which is typically glossy, but lightly grained. A dremel tool will leave a kind of smeared look (like a poorly cleaned window) since the pad is so narrow. I usually polish with an orbital buffer and finish with a scotch pad to get the grain. The underside is sand-blasted. Would love to hear what others do.

Any time you remove the finish on the metal you need to protect the surface. So any zinc coated parts should either be re-plated or cleared. Chromed or stainless steel parts shouldn't require clear unless rust has eaten through the surface, in which case they should be re-chromed, or replaced, but could be cleared if it's minor and not really noticeable.

See the following article on rust-proofing metal parts. There are several options other than clear coat (specifically wax) that the high-end auto restorers use.

http://pinballrehab.com/1-articles/tools-and-supplies/237-rustproofing-metal-parts

Everyone has their own methods based on the tools they own and personal preferences. Just go with whatever works for you.

Zinc-coated will have a mottled gray color. The ball trough on wpc games is typically zinc-coated.

A good tip is to separate whats been chrome plated, and what has not.

Taking any abrasive, even some polishes, 000 steel wool, etc, will always scratch the polish...although some time there is no choice. Remove all rust, see thread on Evaporust etc., dirt, and clean. Buffing can be done by hand, dremel, but best is a Stitched wheel bench mounted with Green Zam or white...do not use red, it is carcinogenic.
Clean of polish with a de-greaser, or double glass ultrasonic.
There are other polish mediums for stainless steel, but more work to polish.

I have had quick good results on a lockdown Bar with a sanding "Sponge"..a few minutes, and a nice satin finish.
I mask off with tape the polished lip.

If sandblasting is not available, and the underside of the lockdown bar is clean and rust free, but your are not happy, a rustoleum silver, with a little texture will work. I use this on the inside of leg restorations...Sometimes I just paint the interior textured flat black, or a cabinet color match.

Another great product is Everbrite coatings and cleaners. I has some posts that i tumbled and polished
on an older game and they would always dull after a year or so....something in the metal that was cast.
Everbrite makes an invisible rock hard self leveling evaporating layer.
Not strong enough for continuous ball wear...the product is used in Brass Hand rails like in Hotel casinos, so its pretty durable, but I coat many small polished parts...fast and easy, and locks the shine in, and much easier then a lacquer.

Your lockdown receiver, depends on how far you want to do. You can remove clean, satin, and re install, or sandblast, or even get chrome plated...up to you.

Ventilation, and masks are important.

Practice techniques on some old legs.....buffing, scotch pads, hand dremels etc...a good way to go to see all the possibilities.

I like the Everbirte stuff, easy to apply and gives good protection. For areas that receive heavy abuse I prefer Glisten PC from POR. It's a two-part auto clear that is rock hard. It is more difficult to work with though and requires use of a metal prep when used over polished metals.

http://www.por15.com/GLISTEN-PC_p_45.html

I'd like to learn more about this too. I'm about to have two machines apart for PF swaps, and I'd like to start weighing options for cleaning / sand blasting / etc.

Perhaps some pictures would really help, perhaps 3 of the "zinc-coated" from different eras so we can get a sense of what types of parts are zinc-coated in different eras.

thanks!
-mof

Sorry no pictures. Standard zinc-coated parts have a dull, mottled gray look. Data East, on the other hand, used a lot of parts with a golden look with hints of red and blue (sounds like I'm describing a wine). These parts were originally electroplated using zinc yellow (zinc plating with a yellow chromate coating). And that's the extent of my knowledge, so maybe an expert can jump in.

Any zinc-coated part is going to have the same issue, if you use an abrasive to clean it you risk damaging the coating.

This is my best friend regrain lock down bars, metal parts etc.

0038078-23.jpg

http://www.amazon.com/3M-Scotch-Brite-Fine-Finishing-Sander-9416NA/dp/B00004Z4DK/ref=sr_1_1

Get various grit

Would this be a good option for a stainless steel part that you de-rust, and polish on the buffing wheel?
Is it toxic (to your respiratory system) like auto-clear used for playfields?

-mof

It does work on stainless steel (requires the AP 120 metal prep) and does have pretty much the same precautions as auto clear (slightly different if you brush vs spray).

http://qr.absolutecoatings.com/QR-assets/downloads/POR15/GlistenDirections.pdf

Good point, if I protect my respiratory system and skin, I can brush this stuff, and not worry about 'not having a spray booth set up'. I think I'll do it. I'd like to protect a few smaller metal parts that get polished and cleaned up, and know I won't have to treat them again -- such as the prop arm, or Gottlieb brackets under the PF, or perhaps the trough components...

-mof