Kansas City, MO
Quoted from SteveFury:Looks like mud dauber wasp nests.
If it were mine I'd disassemble the parts and clean the corrosion with wire wheel and polish it with #000 steel wool. Then apply a coat or two of Miniwax paste wax. The paste wax prevents corrosion. Don't use car wax because it offers no corrosion prevention.
The paste wax is strange stuff. I discovered this a couple decades ago working on antique radios. I'd wire wheel the steel chassis and polish with steel wool then wax. If I waited to apply wax for more than a few hours the steel would begin to rust. Those old chassis treated decades ago are still rust free.
I found it by wire wheeling the protective coating off of a set of nails and trying various products. Car waxes rusted right away.
amazon.com link »
You can pick a can up at any hardware store.
I used the same process to clean up my mouse-pee corroded Gottlieb Spirit of 76 score reel:
ScoreMotor.JPG (Click image to enlarge)
It's interesting, this discussion was had before. I use Evaporust to remove rust from parts. I've used it on many lockdown bar receivers that always seem to be very rusty.
I've never done anything to protect them after the Evaporust bath. None of them have ever rusted again.
A wire wheel is going to remove the corrosion but I think the Evaporust neutralizes it where it won't come back.
