WED72HEDW1 Dryer Motor intermittent

[griinder]

I have a Whirlpool duet dryer that stopped tumbling. No error codes. I hear a relay click and motor makes a thud. The drum turns maybe a half inch then just stops. No humming or grinding. I took the belt off the pulley and turned it on once or twice and the motor did the same thing. I disassembled it to investigate further. I cleaned up the rollers, and the belt appears to have tension. I do not see a belt switch. I metered the thermistor (rectangle sensor) and it had continuity. I also metered resistance across the thermal shut off and read around 10k. I pulled the motor out and and bench tested it by applying 110v to pins 4 and 5 and the motor seemed to spin up nice. I only did this once. 
The vent was pretty packed with lint, so I figured I'd reassemble and try again. Unfortunately I got the same result. I did then toggle the start button 15-20 times after reassembly. During those 15-20 times it did spin up the motor and drum twice during that. I assume I should check for consistent power at pins 4&5 of the harness next. Both when it spins the motor and doesn't.  Which relays should I check? If I do have consistent power at the harness when the motor doesn't spin, is it the motor? If I dont have consistent power where should I look next? I suppose I should also bench test the motor a few more times. Maybe the one time I bench tested it was one of the "lucky" starts. Looking for more direction and suggestions. 

[MrApplianceMatt]

Pull the main control board out of its shell and look for the scorch mark under the motor relay. These Duets are known for this relay going bad due to crappy solder used. If you catch it early enough, you could reflow the solder at that relay with better solder.