The switch for the right sling in my ACDC stopped working. All common drive and return switches in the switch matrix work as well as the coil when tested. I do not see and obvious bad connections at the solder points. Tried cleaning the contacts with a business card to no avail, and my DMM is out of batteries (need to pick some up, wanted to get this question out to the geniuses first). Do these switches fail frequently? Is there something dumb I'm not doing? If it needs to be replaced, how bad is it to do? I'm a noob and want to learn. Thanks all

Bump for the night crew. Just picked up batteries for my DMM so will post results shortly.

It does not work in switch test (#27). Wiring continuity appears intact within the switch mechanism, trying to trace to head now. obtaining low resistivity across all connections and similar results across the diode in the working and non working slings (~580).

Ok, so I hope I did this right. Testing with a DMM from the driver wire in the head up to the diode in the switch reads 1 ohm (same reading as just touching the leads together). Same for testing the other side of the diode to the switch return in the head. I interpret this as complete wiring continuity, so wtf?
For clarification, I have zip tied the switch shut for these tests, so I think my switch is clean and apparently functional (but not ). Also, all other switches are perfectly fine.
Thanks for the help guys!

Diode was it, hairline break in the wire that was completely invisible and just past where I connected the leads the first time! Thanks all, guess I have to buy a solder gun tomorrow.