Safety first: Disconnect power before removing any panels. Moving parts can cause injury.

Steps to diagnose:

Check drum movement: With the door open, try to rotate the drum by hand. If it is very hard to turn, suspect seized rollers or an idler pulley.
Access drive system: Remove the top and front panels to expose the dryer drum, belt, and motor.
Inspect belt: Look for a broken or off-track belt. If broken, remove remnants and install a new dryer drive belt routed around the motor pulley and idler as per the service diagram.
Check rollers and idler: Spin the drum support rollers and idler pulley by hand. Replace any that are noisy, rough, or seized.
Test motor: Inspect the dryer motor for burnt smell or visible damage. With power disconnected, check winding resistance. Replace the dryer drive motor if windings are open or if the motor hums but will not start.

Reassemble panels and run a test dry cycle to confirm that the drum turns and 3F is cleared.

Dryer drum does not turn; 3F appears when attempting a dry cycle.

Possible Causes