Hey Theo,
We checked for spark just before testing the coil, and those numbers were weak, which meant installing a new coil... which came with attached leads.
They're strand wire (cable) in an insulated sheath, cut to length, and pop the old ends on (the old lead ends have a threaded 'spike' that drives into the end of the lead).
Is there a resistor in there that I don't know about?

Maybe I should sand the contacts in there a little?
Spoke with a guy up here who seems to think it's my primary jet, and that it need an ultrasonic cleaning to really tidy it up...
I dunno about that... he runs a business, and will likely want to charge me... not that I'd mind if it sorted the low end out.
Pulled the carbs (yet again) tonight, and gave a
very gentle reaming to the primary jet with a size-smaller drill bit, as had been suggested by one of the 'bike shop boys',
but after reinstalling them and fitting a new inline filter with new fuel line (clear, so I can see any junk in there), the same problem asserted itself after a short ride.
It's like there is a vapour-lock at low speed, especially just after stopping... and I get an air bubble in my line sometimes, too... it used to be in the filter, but I see it in the line, too, now that it's clear.
Bah.
Nice fall day to be out wrenching in the driveway, tho... see, I don't even have a garage to go feel foolish in! You're a step up, there.
Thanks for the tips,
Peg