roper dryer mod: REX3614JWO hard to start and turn, stops working after a couple of minutes, won't start again until it cools off, than stops working.

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Replacement parts for WHIRLPOOL REX3614JW0 | AppliancePartsPros.com

Sounds like your motor is overheating, tripping it's internal thermal protect and then you have to wait for the motor to cool down before re-starting.

Often this is caused by the motor being on it's last legs.

Try turning the drum by hand in the correct direction. It should turn fairly easily. You may want to do this on a couple other units to get a feel for it. This checks if there is a drum mounting problem that is overloading the dryer.

Check that he seal between the blower and the motor is OK so that hot air is not blowing back onto the motor.
Also check/clean your vent system so there is no back pressure.

You could also check the voltage (L1 to Neutral) should be 120 volts.
Low voltage will cause the motor to overheat but usually it would not start. This is a very rare fault.

If all OK then replace the motor.