The easiest way I have found to remove the varnish/wax from the L brackets is to drop them in boiling water for a few minutes, bolts, nuts and washers too. Use an old pot though as it leaves residue in the pot. I have painted a few Bally transformers and they look nice in satin black, but then I heard painting is bad because it prevents heat dissipation. The older Bally transformers are not sealed on the top like the Bally/Wms so it's tough to get the crud from the top of the windings. An old timer pin restorer told me he steam cleans the guts in his EM games and they come out like new, so I might try it on a bad transformer first just to see if it works.