The thing finally misbehaved while I was measuring it.
Here's my proposed e-mail to a few well-recommended HVAC companies tonight.
Subject: Request for bid
1982 Bryant Gas Furnace
Product 397HAW060140 ACBA
the SPDT pilot-flame sensing switch intermittently fails to power the main gas valve coil. Also, it always powers the gas valve pick coil, so the spark module runs the whole time the main burners are on.
The switch seems to be part of the pilot assembly and I don't feel qualified to work on gas piping so I'd like to know if you want to bid on replacing this switch assembly.
If so, I'm hoping you can come out on Monday or Tuesday; I can probably coax it to work that long.
I'm in the xxxx area of xxxx.
I look forward to your reply.