Long, long time ago when I was 19, worked for a medium sized publishing house who at the time were using Apple Mac’s for their operators to input data (the part I worked in handled all the patent applications for the EU). I used to ‘repair’ the Apple Macs - you can’t really ‘reapair’ a Mac as such, even then it was modularised so once you had isolated the card it was a case of swap it out, suck it and see.
Anyway, a common problem with the original Mac Plus was that the built in CRT had a nasty habit of blowing (it was actually the electrical distrubance calused by the lift in our building that was actually the real cause of the problem) and part of my job was to replace the CRT’s (and anything else that went wrong tbh - software / hardware ‘engineer’ = dogsbody).
Once you’ve cracked open the case on a Mac plus, the first thing you should do really is discharge it - there’s a special tool you can use to discharge the CRT before replacing it - you must never forget or you stand to get a belting great shock from the CRT as you start messing with it - guess what? One time I forget and when I stuck my hand around the claw-like gripper that keeps the charge in place on the CRT I got belted with the CRT disharge - 18000 volts? summit like that. Got thrown about four feet against the wall behind me - it hurt, a lot.
That was the same place when one day when I was asked to look at a hardware problem with an OCR scanner. Stripped the casing down to get at the bits of paper stuck inside with the machine still turned on - I had long hair at the time and didn’t realise that as I was leaning over the OCR kit, my hair dangled into the live parts - got a f*cking great shock in front of about twenty girls who worked in the department and had to keep my mouth shut and pretend like nothing had happened…