Panel has 100 amp main but the main service wires appear to be 60 Amp.
Can you tell from the pics if the service wires are 60 amps?
House was built in 1955. Those are the original and appears that the electrician didnt update the main wires.
I attached the sub panel just for your viewing pleasure. It took my 10 minutes to remove the rusted screw. Harry home owner special.