Due to the age and sound of complaint I'm going to have to point towards a motor on this one. Sounds like it may be overheating and cutting off on its overload. When it stops are you able to start it back up immediately or does it take 30 seconds or so to work again? If so and after a time and you hear a clicking sound that could be the ove r load reseting once it cools down

I do not see any kind of relay involved on this model. There seem to be 2 possibilities I can think of... bad centrifugal switch in the motor, where for some reason it may be broken or temporarily failing, now this comes as a motor assembly. Or number 2 would be a bad timer, could have a couple dead spots in it causing it to fail every so often.

To test the timer sometimes they give you a contact chart in the schematic for the machine found in the console. It's normally tested by continuity and machine the contacts with the chart and whether they are open or closed at certain timer positions. The way the motor fails you'd have to check voltage on your motors centrifugal switch. This also requires a schematic and can be fairly difficult. It is best to remove the drum and alligator clip leads to the terminals if possible to find out which side we are losing voltage from.