I recall from my childhood next door neighbor who was a TV repairman back when they had tubes and could be repaired. I was watching him repair one of our TVs and he said that sometimes capacitors or other parts will get too hot when failing and shut off. Then when they cool off the radio/TV restarts. He was showing me how he did the diagnosis by using Freeze Spray from a can on various components until he could figure out which one was overheating.