Chosen Solution
Dryer is making a buzzing noise when pressing start. With multimeter, I checked the start switch, timer, thermal fuse, door switch and all were good. Replaced the motor. Now I can get it to start when holding the start switch and door switch and turning the drum by hand. The motor will also start when the drum is out. When the drum is in, it still just makes a buzzing sound and won’t start. Did I maybe get a bad motor?
@alessi08 You say that it starts OK when the drum is out or when you rotate the drum manually on starting so I’m wondering if there is a problem with the rollers or perhaps the idler puller applying too much tension on the drum or belt. Do the rollers spin freely? Does the drum rotate freely by hand when the belt is removed? If they are OK then it may be the motor. With most electric motors for dryers there is a start winding and a run winding and what happens is that current flows through both windings on start up to create sufficient magnetism to overcome the inertia from the at-rest position. Once the motor gets up to speed then an internal centrifugal switch in the motor operates and disconnects the start winding as the motor can run on the run winding only. Also the start winding has thin wires as opposed to the run windings thicker wires and you don’t want the start winding to burn out through prolonged use. There are videos on YouTube that show how to test a Whirlpool dryer motor but you may need a clamp meter to test the current on startup and run. It may be a faulty centrifugal switch in the motor not reconnecting the start winding when the motor is not operating. Also sometimes there is a tech sheet in with the dryer taped to the body inside somewhere and this usually has the wiring diagram as well, which may help. I found the tech sheet part number for your model 677818L but unfortunately I can’t find a free one online to check
