A very interesting YouTube channel is daitocamera, which deals with repairs of mainly newer cameras and lenses.
The language is Japanese, but the videos are informative even without any knowledge of the language.
Channel info (Google Translate):
Channel information:
This video shows how to take apart a junk or nearly junk camera and see how it works. If possible, it would be great if we could repair it and get it working again!
This is an uncut, automatically uploaded video recorded live, but I hope it will be of some help to people with the same hobby.
Some episodes are quite experimental, and some of the things I say are wrong, but everyone, good kids and bad kids, will take it apart!