Thanks again for the info/ links on your site Tegger!

Well - replaced ignition switch is working like a champ, and I resurfaced
my old one so I have a spare if ever needed. I bought the little button for
the clutch interlock switch, but still can't manage to get my fat hands in
to pop it in the hole, so I had to revert to duct tape ball.

Gremlins reappeared - intermittently. fuel pump would run - or not - with
check light. So I pulled main relay today. I couldn't identify any cold
solder or stress cracks, but about half the connections had the "not enough
solder" condition as described. Also one of the double contacts had a
blackened area that may have had some heat/ arcing problems.

I didn't have a desoldering gun, so I just cleaned, fluxed & melted existing
solder & added to it to fill in. It may not last as long - I don't
now - but it seems to be working right so far.