The radio is 74 years old. Components inside simply age out.
To give a little more insight on what typically happens:
The circuit that creates the higher voltage for the vacuum tubes has a oscillating mechanical device "vibrator" with contacts that usually corrode and stick over time.
There are several capacitors that most likely have aged and failed or changed value. Most are simply replaced with modern ones.
Rust, dirt, dust, spider webs, you name it. The radio will need a good cleaning inside.
The speaker cone and voice coil probably have dried out and cracked and need repair.
The tuner string usually ages and breaks. You notice this when you turn the knob but the needle doesn't move.
Even after doing the above you may hear pops and cracks while tuning like July 4th fireworks (microphonics) which can be caused by dirty, bad or corroded tuner bearings.
The list goes on....
This is why you want an experienced radio serviceman and not a computer tech to work on your radio.
Labor is a lot of the repair cost.
