Dryer timer will not advance

The problem is the timer will not advance in auto. Unfortunately, I am troubleshooting without a schematic. First I replaced the thermostat 3387134. Then, I replaced the timer with a refurbished one and it still does not work. The heat cycles on and off correctly and the timer will spin in auto if I disconnect one of the red leads to the thermostat 3387134. And now the timer will not spin in time dry either. but it will still spin if I disconnect one of the thermostat leads. Also, I have 120 V AC across the timer wires and it goes to 0 Volts when the heat turns on.
Any suggestions or is the dryer at the end of life?
Thanks

Brian, did you ever figure out what the problem was? I’ve got the same dryer with the same problem.
Hope to hear from you.
GJS

— Begin quote from Brian7780;231763

The problem is the timer will not advance in auto. Unfortunately, I am troubleshooting without a schematic. First I replaced the thermostat 3387134. Then, I replaced the timer with a refurbished one and it still does not work. The heat cycles on and off correctly and the timer will spin in auto if I disconnect one of the red leads to the thermostat 3387134. And now the timer will not spin in time dry either. but it will still spin if I disconnect one of the thermostat leads. Also, I have 120 V AC across the timer wires and it goes to 0 Volts when the heat turns on.
Any suggestions or is the dryer at the end of life?
Thanks

— End quote