To be honest, I’ve never subscribed to channels for this purpose. I tend to just search the whole of YouTube when I’m struggling with something like this. Though agree completely that YouTube is a great resource for getting some insight into things like this.
Searching quickly for a solution, esp if you are under time pressure is a reality we all face, but knowing who to trust is another. Some videos are just far from ideal, ignoring electrical safety steps, breaking plastic tabs, etc.
I’ve also found that while an item brought in might present one problem, it might have many other issues, and having a broader awareness of what can go wrong and what to look for is very beneficial.
Spare TIme Repair, as an example makes many electronic, electrical and mechanical repairs when overhauling a CD player. Often fixing parts that are failing like poorly lit screens, and servicing all push buttons.
Knowing what other surprises lurk beneath plastic covers is also a benefit. Some brands have different internals for the same model no. Depending on country of origin, age, manufacturing batch, etc.
I’m sure we’ve also seen some horrific repairs in sweat shops with little consideration for repairer safety.
A Wiki would be good. It will though overlap a bit with Wiki Content on Restarters.Net which is another fantastic source of info we should list along with iFixit.com and others.