You've tested for continuity with a DMM?
EDIT: OKAY! I noticed an error in my schematic, and then rechecking the updated trace, the whole thing still didn't make sense.
So I re-examined the updated trace and my schematic and... well, even before the missing link was discovered, my schematic had some substantial errors — since rectified.
I was fixated on how I thought the circuit was, so failed to see how the circuit truly was — all stemming from ground around C2 and R3.
Errors fixed:
- C2&R3 were backwards, now swapped
- YSW Lug 4 went straight to ground, it does not, and it wasn't connected to LIFT 3&6
- LIFT SW 3&6 went straight to ground, they do not
- Missing trace, added
I hope I haven't missed anything else.