As vintage computers age, there will be growing checklist of things to do on a newly acquired system 30 years old which is ailing.
We could begin with learning to identify parts.
Know when they have burned up. Note the smell, the color, the temperature.
Look, listen, smell, touch, know when something isn't right. Know when it is.
Understand keyboards, cleaning, resoldering, exercising them.
Reseating cables 10 times to ensure cleaner connections.
Measuring power supplies and voltages and ripple.
Buffing chips and reseating them in sockets.
Making sure the system has the right chips in the first place.
Checking all screws and hardware for secure-ness.
Removing metal whiskers, my old II+ grows them like hair on hippie! I kid not!
Ensuring the all the basic components and accessories are present.
Doing adjustments in accordance with the manuals.
Know programmable chips from non-programmable ones.
Basic soldering and reflowing. Know what good solder connections look like, and bad ones.
Learn how to intelligently swap chips, so that you may solve the issue with 2 or 3 swaps absolute tops. Ram excluded of course!
Understand how to use a DMM for basic problems, and a scope for more involved issues.
Basic troubleshooting techniques (this means reading manuals and thinking a problem through too). It also means things like replacing/removing cards and bringing a system to its most basic configuration and testing as you build it up again. Things like that.
And finally, everybody that works on vintage computers should have basic electronics knowledge, know volts & amps & ohms & watts. Know Megahertz and Gigahertz, and in the case of really old systems, kilohertz. Know how contacts behave, know transistors, resistors, capacitors, diodes, switches.. I'm not saying calculate beta for an NPN, but just know the parts and their functions. Know how to identify them. Do you know what analog is? What digital is? How about AC/DC/RF/Composite - are these the same or what?
A lot of this stuff has varying degrees of intensity to it too, and requires good judgment stemming from some technical experience. You won't use a dremel sander on a 40-pin dip that goes in a socket, but you could use it to buff a screw ground-point or something.
How much do you buff a gold edge connector? Till it turns light? Silver? Almost no change?
When do you use contact cleaner? How much? Spray? Brush-on?
What types of lubes on moving mechanisms like drive motors and doors and heads.
Understand basic physics, that will help a lot.
And finally, everybody needs to learn to use the reference material at hand. OR EVEN BETTER, learn how to find it. The internet is just stuffed with information. Learn how to present a problem to the forums, learn precision communication that is concise.
Fire and Brimstone everyone! Have at it!