Hey all, here's my final update and resolution:
After 4 months in the shop at Grand Prix Motorsports in Littleton, Colorado, my 2020 SR/F Premium was finally repaired. That dealership also buys used motorcycles, so I negotiated the sale of the bike to them. After 4 months, all I wanted in the worst way was for this to finally end. I didn't haggle about the low price; I took their check and ran away as fast as I could.
I've been riding motorcycles for more than 40 years, and have never had an experience like this. It's not possible to get a service manual; all Zero motorcycles must be serviced by Zero dealers. I have precisely one Zero dealer within two hours drive of my home. The dealer relies on Zero to diagnose problems remotely from California. Zero typically takes a week or more to simply reply to the dealer, each time. Zero sends replacement parts in such a way that it typically takes a week or two for a part to arrive.
It was not possible for me or anyone other than Zero to diagnose the problem, which apparently was an MBB problem.
Zero verbally chastised me for doing "unauthorized" modifications to my motorcycle, by installing aftermarket LED running lights, louder horns, and the eMoto Design dub-J charging kit. I didn't realize I needed Zero's authorization to modify the bike. Somehow I thought it was my bike...
My 2020 SR/F suffered from problems in rain (throwing codes, Check Engine Light, etc.), in addition to the common problems of front brake pulsing, terribly harsh suspension, etc. The rain problems would always go away after the bike dried out, so there was no way I could get the dealer to see them.
So, with simply the "bike doesn't charge" problem, the bike was in the shop from March until July.
My Yamaha Super Tenere ES has been through rain, sleet, hail, intense sun, deep sand, and more, for nearly 51000 miles. It's been into Mexico three times (it likes tacos!). I have had no problems whatsoever with that bike. My Zero cost far more, and took me a grand total of 9385 miles.
I will never buy a Zero again. When Yamaha produces electric motorcycles, I'll be first in line.
So long, and thanks for all the fish,
- Fred