After swearing at it on the day of the engineer's trip, and off it the day after, I started investigating the problem.
I noticed that on-line pictures of the distributor had a gasket underneath it, something that mine didn't, and I realised that the thickness of the gasket would raise the distributor up, and therefore effectively make the button sit lower (as the button, and the shaft it sits on, is not attached to the distributor but instead passes through the middle), and with the button sitting lower the cap could fit on properly instead of just sitting on top (exactly why it was working before when it was just sitting on top, I don't know. Just lucky, I guess).
The cap seemed to be almost three millimetres too high, so I cut out three layers of 0.8mm gasket paper to pack under it. Oh, while we've got this picture, that's the underneath of the distributor. See that blue wire there? That's the condenser wire. This is where the condenser lives, in a little compartment underneath the distributor. Therefore, to change the condenser, you've got to remove a bit of engine cover, the distributor cap, the distributor button, the bloody distributor, turn it over, and then unscrew and at least loosen if not remove (depends on what connection the condenser has) the bolt in its insulated housing. While the engine is quite hot.
That bolt, incidentally, has a wire soldered to it, and soldered to the distributor at the other end, so if something happened to it, there's sweet fuck-all you could do about it on the side of the road. It's an old-looking wire, isn't it? That's cloth insulation, just like great-great-grandpa used to make. Just the sort of thing I want to be regularly shifting about whenever I think "Maybe it's the condenser?".
Yeah, stupid spot, and I'm going to be moving the bloody thing.
Well, here's the distributor on, with the gaskets under, and the cap (not shown) now sits on much more firmly. I had to replace the bolts for the distributor, as they had been rendered too short.
I seem to have put the gasket papers on upside down. I can see the paper jutting out oddly from underneath.
Fuck it. It can stay like that.
With the condenser, the positive end hooks up to the wire that goes to the distributor from the coil (not the high-tension wire, the normal one). Wires being what they are, it doesn't matter where
on the wire it hooks up, at the start or end or anywhere in-between, as long as it does. The other end of the condenser goes straight to earth. Just good, simple earth. Following the same argument, this means I could hook up to earth anywhere
on the bike, even on the rear mudguard if I like, as long as I do.
So I made a mount, and stuck the condenser over the coil. Nice, simple, and easy to get to. Even looks nice and neat.
The bike was very hard to start, but happy to run once started. I took it for a test-drive, and when I got back tried to re-balance the carbs, since I had fiddled with them in my efforts to get home and the setting would be all wrong now.
Couldn't start the bike on one cylinder, at all, and then I couldn't start on two, either. And my indicators and tail-light weren't working.
After repeated "Hard to start, but will run happily once going", I started to suspect the battery. I'm often lax in checking the battery, and it's been quite hot lately, so the fluid has fallen a bit low. The battery's also three or four years old, and may be on the way out. Low battery voltage also explains the indicators and tail-light--they're LEDs, which can be fussy about voltage.
I topped the water up, and after a few kicks started her up again.
Running fairly well, although I'm noticing the battery charging light won't come on while revving. It's not blown, and the circuit works--it does come on whenever you switch the bike on before starting the engine, but then goes out when it's idling. It's another mystery, but one that won't affect the engineer.
A bit more revving, and then a bloody stream of oil starts flowing out from the generator housing. For fucks sake.
Take the generator out, and check the O-ring. Seems in decent shape. A little bit of oil had always leaked from around the generator, and I was thinking I'd need to do something about it before its blue slip. The leaking must have cleared a wider path.
Couldn't replace the O-ring at the local bearing place, and the old one seems in good shape anyway, so I'll just re-use it, but this time have it held in with gasket goo, with more goo on the generator, to make a good tight seal, and then leave it to set.
With that all done, I start the bike up again and look for any oil... No, can't see any, looks like I've fixed the leaking. Good. Now let's see if I can start her up on one cylinder so I can adjust the carbs.
And she fucking bit me again.
To explain, the kick starter is between the bike and sidecar, and it's quite a tight fit. When kicked, your foot goes below the level of the floor of the sidecar. IF your foot slips a little on the kickstarter, your little toe will end up underneath the metal sidecar floor, and then IF the bike fires and kicks the kickstarter back up, it will ram your little toe right up into the floor. With great force.
This is very painful, and it's the third time over the week it's done it.
My little toe is now slightly swollen and a quite interesting purplish red colour, and I'm taking some days off.