Have been reading FAQ on forum to try and gain more info re problem and to date not noticed anything re reverse polarity.
My suggestion was to get you thinking "outside of the box", not necessarily to pin-point the specific cause although that would have been favorable. . Of course you wouldn't connect the battery in reverse. According to what you've told us - all the wiring checks-out. Additionally you've cleaned the elec. connectors. Therefore there is a real possibility (sitting here thousands of miles away without the luxury of having your bike in front of us) that if you removed the terminals from the block to clean them and especially if several were removed at the same time - the polarity could have been compromised by replacing them out of sequence. It's not that difficult to do and at this point can not not be discounted by anyone offering solutions.
Challenging times, these vintage bike electrics. Diagnostic Tree-charts are great when it's all shiny and new. Put old bikes into the hands of several others prior to your obtaining them and with virtually no knowledge of what's been "HACKED", you have no alternative but to think in a different mind-set once the manuals diagnostics have been exhausted. Keep in mind something else; Getting meter values per the manual (for example pg 243-K11) doesn't end at merely getting a reading. With so many combinations it's VERY easy to get a "-" reading, think it's merely because you have the probes reversed, change the probes polarity, see the reading you want to see and not realize that MAYBE that pair is reversed (somewhere). Ask me how I know.
Another Theory; If wriggling the Kill-Switch gives intermittent/inconsistent readings then I'd be suspect of a high resistance constant contact (a partial grounding even when ON) which could be causing a conflict within the igniter circuit itself. If not the switch then a similar "short" elsewhere. A single strand of wire can act as a "jumper' between two separate circuits and potentially leave you with the issues you are experiencing. Nothing in FAQ's regarding that either but it doesn't mean there haven't been others with a similar problem. Just means no on has supplied a viable solution. Maybe because they discovered something as embarrassing as a couple of wires reversed after 12 pages of thread provided nothing.
Remember the "the Fun" with the old style Christmas lights. One "Blue" burns out and ALL the blue are out. Then you had to pull every blue bulb sequentially - replacing each with a known good bulb until all the Blue come on again. And it's always the last bulb you check that's the culprit. You can not discount anything until you've actually fixed the problem.
"You don't drown by falling in the water; you drown by staying there."
