Re: deja vu @Alan Brown
You may remember the old BBC computers, where one had to take off the cover and push all the chips down into their sockets periodically - constant on/off switching caused the chips to work loose. I never had the problem, since I didn’t ever switch mine off, except for maintenance, or installing a Solidisk board.
There's an old story of an engineer being called out to fix a machine, might have been a computer or some other machine, and after rthe machine was working again, the manager in the department which ran the machine came in spluttering and shouted "You charged us 339 quid, when all you did was to hit it with a hammer!" "Ah." was the reply: "30 pounds is me standard call out fee. The 300 pounds is for knowing exactly when , how and where to hit it."
I can seee my own way out - I've been calleed away to look at an Altair 8.