I have a rather old Frigidaire 1-18 electric dryer. The nameplate on the back has what appears to be an incomplete model number, as it only says "DEC" with no numbers. The serial number is 70DK6670. It was probably built back in the 70s.

A few weeks back I was drying clothes when suddenly it began to make a very ear-splitting squealing sound. I stopped the dryer, pulled it out and opened the back panel to see what I could find. I took out all the rollers that support the drum, cleaned and re-greased them. I inspected the belt but it seemed to be ok. I tested the motor and it also seemed ok. I put the whole thing back together and it ran as normal again. I threw a load of clothes in for two hours and it dried them fine. The next morning I washed my bedding and threw the comforter in the dryer. It ran as normal for about an hour and then just suddenly...quit when no one was touching it in mid-cycle. The timer was still set for another hour but I couldn't hear if it was turning or not. I checked the circuit breakers and they weren't tripped. I looked inside the dryer again and manually turned the drum. The motor and the drum turned easily. I took the belt off and tried running the motor by itself and nothing happened. I turned the timer to several different positions and still nothing happened. I turned it to the off position and the buzzer went off, so the dryer is definitely getting power. Would this possibly be a burned up motor or would this more likely be the door switch or something? It was just weird because no one was near the dryer and it was working fine. Then suddenly it quit. Can anyone help me?