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I have noticed for old equipment that was designed for commercial/industrial use (jukeboxes, PA amps, broadcast equipment) and which was designed for 24 hr. a day use there is always fuse protection in the power line and usually additional protection such as a B+ fuse. The notable exception is Hammond organs.
However most consumer equipment seems to have no protection.
I always retrofit any old device I repair with a fuse, even table top plastic radios. The only ones I don't are series string radios with a tube rectifier as the rectifier cathode is designed to be fusible in case of a short and usually a portion of the rectifier filament acts as a fusible/surge resistor.
Also I don't let there be anything on the power line in the set before the fuse. If there are noise suppresion capacitors across the line I just remove them and have had no trouble.
I replace all electrolytic/paper capacitors and any old silicon rectifier diodes before using a piece of equipment. I have had too many failures of these old things from previous experience to trust them. One was a shorted capacitor or diode in a Harman Kardon A-300 amp which worked perfectly on original components for years but luckily had a fuse which blew when the short occurred to prevent serious damage to the power transformer.
I also have seen too many cases of burned/shorted wiring in places like Hammond organ tone cabinet connectors, and melted 5U4 tubes due to shorts where damage likely would have been minimized had a fuse been in the unit.
The only time I actually experienced a fire was a flyback fire in an RCA CTC-31 when I was a teenager. Everything inside the HV cage was burned and melted. Luckily there was no other damage to anything else but that was very scary.
Another potential problem can be (i am theorizing) when the enamel insulation on magnet wire degrades due to heat. I have had several motors in electric fans burn up and my theory on this is that the motors were overheating for some reason in use which led to the insulation breaking down to the point where a short finally occurred across the windings and burned them up. This sounds like the kind of failure which may have occurred on Dave's set.
If a motor has seized due to lack of lubrication and the windings look discolored, even if I can relubricate it and get it turning again I just replace it due to perhaps the increased possibility of a short.
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