Big v small. You are unlikely to get called out to urgently fix a snag on a Cessna 150 at three in the morning

The heavy maintenance people earn their money at all hours of the day & night. Ok, I take your point about the body count after a big mishap. I was actually thinking about the Korean cargo accident at Stansted. I really had a job fathoming the accident report.
So I can pull a radio out, but I can’t replace a duff switch or a broken board even if I have the parts? So, what you are saying is that I would be confined to looking after wiring, breakers and antennae and things? As an aside, I take it that light aircraft are wired positive earth?
I am prepared to believe that I couldn’t make it pay. I currently work in the broadcast industry fixing commercial video recorders and cameras. I could only do a fraction of the work without the spares support and manuals.
I think your suggestion to do work experience is a good one. I am not sure now that this line of work is for me, but it is certainly food for thought. Many thanks Lear Doctor.