Electrical issue with my 73

I’ve been having an issue with the fuse block. It started last summer when my radio would shutoff while driving. The radio is a pioneer din radio I installed many years ago. I decided to buy a new one with blue tooth and all the new software. The other day it shutoff again. This time I noticed the gauges, the clock, and courtesy lights were off too. Checking the fuse block I found that there was no power to about have the fuses. The heater and wipers still worked. I check the batt terminal and at first it was dead but I minute later everything started working again. I decided to remove the connector from the engine side to check the connectors.

For something to be aware of, I had a problem on my '79 when my starter started winding @ 60 MPH. After much, much hunting, I found in the fuse block that, through the years of vibration, a spade terminal had 'sawed' through the insulation on the wire going to the starter solenoid, engaging the starter. If my VOM had not had a needle sharp probe on it, I never would have made contact with the affected wire through the tiny mark on the insulation. Something to consider while you have it apart. Good luck.