UPDATE: So the '81 let me down Thursday afternoon as I was ready to leave work. Ran the "parking lot tests" and they all pointed to the Bean Can. Grrr...
Called Rick Jones at Motorrad Elektrik on Friday to ask for his thoughts on my unlikely and way too early bean can failure. He was as baffled as I.
He did mention the possibility of the coil's HT leads being in contact with the wire bundle that pokes up out of the top engine cover. Said the Hall sender could fail with a heavy voltage spike that just might be generated by the close proximity of the HT lead.
Saturday morning, I pulled the tank and, whoa... the left plug wire was looped and laying on the three-wire bundle from the bean can. Moved the HT lead well away from the harness. Next, I pulled the can for inspection.
Double Whoa... The three-wire harness between the can and the terminal block was smashed. It had been pinched between the front engine cover and an interior web on the timing chain case. Thin does not begin to describe the insulated wires!
Grafted in OEM wire from a small stash of bean can parts, secured everything, hooked up the battery cable and the bike fired right up.
So. I don't know if the HT lead was the issue -could have been- but I'm pretty sure the paper thin wires were broken. At any rate the Hall sensor was not failed. It was the owner's error in routing and pinching wires. Back on the road and it did not cost a red cent.
BTW, Rick mentioned he no longer offers a bean can Hall sensor replacement service. He did say he would consider directing inquiries to me. I have replaced four sensors for four different bikes in the past few months. I have a supply of the Honeywell parts. If you have need for replacement services, give me a shout.
Monte