Glad to see you have a complement of precision test instruments..;-)
Your comment on the IBM Model 80 reminded me of the day I walked into the office (year - probably mid 90's) and they were having a problem with the computer. Just a minor thing - it wouldn't boot from C: and that was the only computer they had (a 286 DOS machine) that they did billing on. The office females were having a cow and asked me to look at it. It would boot from the floppy but the hard drive was invisible - and as far as I could tell, not spinning either - drives weren't exactly silent back then..) So I took my trusty test fist and thumped the case like you would resusi-Annie. The hard drive spun up with its normal noises, the computer booted, I was a hero, and it caused the boss to break down and get a 'modern' computer, a screaming 486 with Win95 OSR2... (which was still there when I left that company 10 years later.)
Thanks for your story.
Percussive maintenance. :)