In the continuing saga of spod versus machine, I have managed to resurrect one of the Commodore 64 beasties. I had previous thought the keyboard was utterly toasted, but it appears to be only about 30% of it - but I had another C64 with a fully working keyboard that wasn't booting up - so I swapped 'em. Job done - one working C64.
Now I just have to work out why the other one doesn't boot up. On inspect inside, some of the chips look...tainted. Like they've oozed out something. Oh well...will have to surf the net and see if I can find a cure.