Apologies in advance for my long-windedness, your patience and expertise is appreciated.

Background: 93 244, LH2.4, 200,000+ miles. Car was originally an auto but I swapped in an M47. Shift interlock stuff was completely removed and the neutral safety switch was appropriately jumpered.

Occasionally the car randomly just wouldn't start. Everything looked fine (battery voltage, etc), but turning the key wouldn't do anything. And then after a while it'd start right up like nothing happened. After a couple of times I realized that wiggling the carpet around the shifter fixed the issue. No problem, my neutral safety switch jumper must have a bad crimp, right? Wrong! :(

Yesterday it finally quit and no amount of carpet-wiggling would fix it. I pulled the kick panel out and took a look. My jumper is fine, no resistance across it. But when I turn the key I only saw about 11.6 volts on both sides of the jumper. A little later it started working again, and I saw ~12.5v at the jumper. Would that 1 volt-ish difference prevent the starter from engaging? If I jump the starter terminal to the positive battery post it starts right up.

The red wire going to the ignition switch shows full battery voltage (~12.5v), but I couldn't see in there to figure out how to measure the voltage on the pink wire where it comes out of the ignition switch. Is this a common failure mode for an ignition switch? Does it make sense for me to plunk down my hard earned cash on a new switch without further investigating if there is some issue between it and my jumper that might be causing the voltage drop?

And that would mean my temporary carpet-wiggling fix was a red herring the whole time, which is weird.

Any thoughts or advice is welcomed!