I've been an idiot and think I may have fried my battery and starter motor/switch.
Finally got a bit of time this afternoon to do an oil change, clean out the centrifugal filter, replace the perished engine mount rubbers and spring and replace the alternator belt. So far so good.
Anyway, I then try to start it, no noise or movement from the starter but lights out etc. when starter lever pulled. Odd as the battery should be fully charged and the headlights etc. working fine.
Give it another couple of pulls, starter lever goes a bit slack. I get out and while I'm still pondering matters I hear grease sizzling on the battery terminals. Whip off the earth but not before there's a pretty nasty burning smell coming from the engine.
The starter lever had obviously got jammed and the starter was drawing some hefty current even though it wasn't turning.
A quick check of the engine earth strap revealed at least one of the starting issues - I hadn't put a washer behind (as well as on top of) the eye of the strap when I bolted it back on to the rear crossmember and it had got well chewed up as I'd tightened the nut, so a poor earth was probably the reason why it wouldn't start in the first place.
Question now is what damage has been done by the sticking starter switch. Dare I give it another go (assuming that I can resurrect the battery with a charger)? The starter lever has freed off again...
1982 aircooled by the way...
Cheers,
Mike