So a bad start button cause the motor to hum but not start unless I spin the motor?
Maybe, but a bad timer contact will reduce current to the motor. You can always bypass the start switch to see.
Steps to a no-run dryer:
1. Check timer contacts for continuity.
2. Check voltage to motor, contacts 4 & 5, (120VAC).
3.Check motor windings for continuity, (2-4 ohms).
4. Check PTS contacts R1 - R2, while pushing start switch.
5. Check PTS relay coil R2 - CT1 for continuity
This is a science, so having a meter is a must.