If you can, post a picture of the one you have.

I found a 1940 Hobbs patent. No mercury.
If the 986642 switch is constructed like the patent, it would be difficult to take apart to repair the wire.
Attachments
Hobbs UH Lamp 01.jpg (90.26 KB, 76 downloads)
Hobbs UH Lamp 02.jpg (78.5 KB, 71 downloads)

Last edited by buoymaker; 07/05/2021 5:29 PM.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."