For the chassis... I recommend not using a polish. The chassis has a thin electroplate and polishes can eat away at it (guess how I know?). Damp rag for the surface dust and such is fine. Then, I suggest a car wax, but, again, not a polish.
Oh, yes, car polish is far too aggressive for a chassis. It's designed to remove the oxidized surface layer of paint or clearcoat.
But a fine polish, such as Mother's Mag and Aluminum or Gorham's Silver Polish has a very mild abrasive which removes very little material, far less than the car cleaners. Not enough to damage the surface. Perfectly safe for silver plate, for example. I've used it on remove hard silver sulfides which otherwise would not give up and die, as well as for removing oxides and sulfides from silver contacts in rotary switches. Try it on a test spot and see what it does.
While one can seal the surface, this is typically unnecessary with a cleaner having a decent anti-corrosion additive. Instead of car wax, one might try a microcrystalline wax which is much harder, less prone to oxidation, and therefore more robust. This is what museums use on metal sculpture to protect against corrosion. It costs a lot more than car wax, and consumers typically can't tell the difference, which is why it isn't widely used in consumer products.
For the socket contacts... I have favored interdental brushes and 91% or better isopropyl. Deoxit is fine for after an initial cleaning with the brushes and alcohol, but bear in mind that if you ever desolder/resolder to the socket contacts later, the temperature will likely exceed the Deoxit's temperature limit. There is no clear answer I have ever found as far as exactly what happens to Deoxit when subjected to soldering temperatures. However, after all of the soldering is finished, some have said that surfaces previously treated with Deoxit can then be recleaned with, for instance, the alcohol, and then the Deoxit reapplied.
The dental brushes are great. +1 on that suggestion. Inexpensive and available in different sizes. Why pay five times the price for the same product with a fancy name and package?
DeOxIt comes in different varieties. The basic formulation is a cleaner, some stearate plus a solvent carrier. The fancier version adds a fluorocarbons, difluoroethane, as a cleaner. The anti-corrosion additive is likely something simple and safe, like EDTA or benzotriazole or something similar. When heated any residue will volatilize. Look up the ingredients and the boiling points. It's not going to corrode anything.
Oxygen and sulfur are the big causes of corrosion.
PS - I think it would also be worth asking the manufacturer of Deoxit if it is approved for all kinds of metals or only certain kinds. IIRC, the original Dynaco socket contacts were cadmium plated.
DeOxIt will work on any metal oxides or sulfides by virtue of the chemistry.
The problem with cadmium-plated chassis, of course, is that the corrosion is toxic, as was the original metal, so the removed material is also toxic. So any company contacted should warn you about the risks.
Cadmium
Cadmium degrades it two ways.
(1) Cadmium + sulfur in the air produces cadmium sulfide (CdS), a green-yellow powder.
(2) Cadmium + oxygen and moisture produces cadmium oxide (CdO), a white powder.
Both are toxic. The lungs well absorb it as does the GI tract. You do NOT want to have it airborne, so do NOT remove it indoors.
I suggest you read up on safe removal, which requires a mask and nitrile gloves, and doing it outside. The cloth/towels/rags are technically low-level hazardous waste, but nobody's going to take you away to the gulag if you just bag them in the trash instead of taking to the hazardous waste cleanup. You just don't want the dust to end up on your clothes and be brought inside your home. That's the big issue.
BTW: the hazard of cadmium is why RoHS misguidedly banned CdS photocells. The amount is trivial and bound in an epoxy layer, so no way is it getting out. But that's the nature of RoHS.
Metal Cleaners and Polishes
Here's a discussion I previously posted about metal cleaners and polishes, with some edits for clarity.
Metal cleaners and polishes are made from a few simple ingredients:
(1) mild acid (commonly citric, sulfamic, oxalic, etc.) to break up the metal oxides, salts, and sulfides so these may be complexed into something soluble.
(2) surfactant (wetting agent) or detergent (cleaning agent), such as oleic acid, palmitic acid, stearic acid, to form soluble metallic soaps which will dissolve in the carrier, and to make the polish spreadable across a metal surface by reducing the carrier's surface tension. A chelating agent (EDTA) are often added to bind to corrosion oxides and make them soluble in a water carrier, but the chelating agent also is a corrosion inhibitor (see below).
(3) solvent carrier (water or petroleum, typically deodorized kerosene or naptha), usually with some petroleum solvent or organic solvent like acetone to better dissolve and remove any polymerized (crosslinked) oils and other dirt, including monomer (the building block for polymers)
(4) Corrosion inhibitor, commonly EDTA or .benzotriazole. Because EDTA is a chelating agent it binds to the now exposed metal surface preventing oxygen and sulfur from binding, hence corrosion inhibitor. Two for the price of one. Saves money in manufacturing.
(5) optionally, in polish, a fine abrasive to assist in gently breaking up the hard oxide layer without removing significant material from the surface.
The remaining ingredients tend to be thickeners and pH adjusters.
DeOxIt is a cleaner, not a polish, and is a combination of stearic acids, again to dissolve and solubilize the metal corrosion, in a hydrocarbon carrier. It's non-abrasive and likely relies upon the mechanical force of the contacts moving against each other, potentially plus the abrasive effect of removed material, to break up the corrosion layer.
The fancier DeOxIT Gold adds difluoroethane to the mix to better remove those metal salts. Chloroflurocarbons are wonderful solvents, which is why industry used them for decades, just letting them evaporate after use and thereby destroying the ozone layer. Difluoroethane is not as seriously ozone depleting as the CFCs it replaced, and it photodegrades in a few years, more or less, and is often used as a relatively safe propellant and cleaning solvent, as long as it is not deliberately concentrated and inhaled.
Because DeOxIt doesn't contain an abrasive it will tend to need some mechanical force to remove hardened corrosion from pins. Again, this is normally provided by the friction of the switch contacts making and breaking as the switch is moved.
Adding a mild abrasive helps to break up the hard surface of the salts, oxides, and sulfides so they may better complex with the stearate and be removed. This is why the Nev-R-Dull wadding polish uses a more abrasive cutting agent to faster remove corrosion. It is also why museums won't use wadding polishes on metal objects, as the abrasive removes surface material, not merely the undesired corrosion.
Electrical connectors can be cleaned using any fine polish, such as Mother's Mag and Aluminum Polish or the 3M Mag and Aluminum Polish, or the very similar 3M Chrome and Metal Polish. Blue Magic is similar, but not as effective. My experience has been these three work better than the common household polishes like Noxon or Brasso, or the Gorham Silver Polish. All of which I have in my house, BTW. The Noxon and Brasso will generally not deliver the same mirror bright finish that the Mother's Mag, 3M, and Blue Magic can create.
Just wipe the surface down with a petroleum or terpene solvent to remove any residue.
I polished the chassis for a Dynaco PAM-1 power supply and removed all of the greenish gunk and left the chassis mirror bright without any damage to the silkscreen. It wasn't great to start, but it looked much better when I finished. I suggest carefully using it in an inconspicuous test spot to verify its suitablity for any chassis.
I moved the L-pad to go before the input, and it worked much better.
