All your comments help and I appreciate them.
The reset knob IS installed at the bottom of the dash. Trying to twist it makes the trip distance wheels (numbers) jiggle a bit but they cannot be reset. So the cable from the reset knob to the speedo must be connected. Just not working correctly.
It must take good hands to reach the knobs. No way around that I guess. If the dealer sends me a replacement, I can look at the new one and get my bearings. I suppose the reversing gear will need to be migrated to the new unit.
It seems it all boils down to those two knurled knobs.
I live in farm country. I could subcontract this out, but all my friends bend horseshoes barehanded like some people fiddle with worry beads. They are not going to fit those mitts into that space. I better figure out how to do this myself. I should replace the speedo with an hour meter like a proper motor and use that to trigger
oil changes. Is that gauge original? Yep, and rare.
Ciao,
Vince