AndrewT, looking for a compendium of troubleshooting tidbits - well just ask me. I have more information in my head than even I can believe. Seriously, these things require a certain talent to invent. For instance, I invented (I am sure I'm not the first) a method of discovering where a break is in a shielded cable. It's usually at one end but my method finds it without cutting or piercing, within an inch or so.
It also helps that I have a degree in Electrical Engineering, have been a radio amateur for over 60 years, and owned an electronics repair shop for many years.