Some channels I enjoy for retro computer/electronics repair:
Adrian's Digital Basement: https://www.youtube.com/c/adriansdigitalbasement
Jan Beta: https://www.youtube.com/c/JanBeta
Mark Fixes Stuff: https://www.youtube.com/c/markfixesstuff
RMC: https://www.youtube.com/c/RMCRetro (he does lots of non-repair retro stuff too, search for Trash to Treasure to see the repair stuff).
One nice thing he does is putting a tiny scope probe symbol on the part of the schematic diagram he's currently investigating.
His "Trying to Fix" videos are a pleasure to watch, and mostly (not always!) deal with older tech or toys. But he'd also try to fix a dead Playstation, for instance. Or a 2010-ish Macbook.
Also it's always mentioned, but CuriousMarc and Ken Sherriff have some amazing restoration videos. In particular the excellent series on restoring the apollo guidance computer.
I recently realized that this kind of video is at the intersection of two of my interests (filmmaking and crafts) so I am, in fact, preparing to launch my own channel. Stay tuned ;)