Hi Turnip, think I know how you feel...!
In my early day's at the Coop - that was after they delivered bread and milk on a horse cart, an engineer loaded a Thorn 1500 into his van, "HOY, Tommy I shouted", brooom.... he was off as though at Brands Hatch, the telly comes flying out in middle of the road bits and pieces all over the darn show! He hadn't shut the door properly... he spent half a morning tracing a faulty capacitor in one of the I.F cans, telly and van were a fair distance apart when he stopped!
I now know what a sick parrot looks like!
Then there was this apprentice, had one of these 1500 in bedroom and fitted an headphone socket, the wire draped over the dropper resistor, one night sizzle, sizzle KABANG and he had his headphones on.
Back on topic.
I'm wondering if condensation sets in on the contacts, I've had this in 455Khz Toko ceramic filters in Ham rigs when they allowed DC on the contacts because of lack of 10nF isolating caps, it causes electromigration, green as heck inside they were!
Dave