Update:

I followed the procedure A. Dalton outlined for a fellow w124 owner a couple of years ago to isolate the K38 relay and S16 NSS from the starting circuit. Still nothing. I turned the key to the start position and jumped directly from battery positive to the middle post on x27 and the engine sprang to life. Wonderful! Except it wouldn't turn off!?!

I could pull the key completely out of the ignition and it did nothing to affect the engine. I wound up blocking the air intake to choke off the engine.

I have verified that the NSS works properly using an ohm meter. The K38 doesn't click at all, so I'm guessing it isn't getting power. I have no functioning dash instrumentation, so that would seem to indicate there's no power on those circuits either. No brake lights, reverse lights, nor turn signals, but the headlights and interior lights work fine.

I cleaned all the contacts for the fuses and replaced all the fuses with new ones. All I could find yesterday were really poorly made Buss fuses. At least they were cheap since I'll be replacing all of them again with better quality ones. I'll pick up some good ones today.

Could the other issues be the result of a bad ignition switch? I searched through the forum, but didn't find anything related.

Thanks again for everyone's help.

-Dean