GE GFDS250EF Manual page 87

Service Mode Tests
(t13) Drum Test:
The control shall start the drum rotation in the forward direction for 30
seconds and the 7-segment display will display "On".
If the test is ran on models which support the detangle feature, a pause
duration including a six second drum motor reversal delay (to ensure an
empty drum reverses) will occur.
Then the control will start the drum rotation in the reverse direction for
30 seconds and the 7-segment display will continue display "On".
Rotation will then stop and 7-segment display will display "OFF".
Note: Opening the Dryer Door will cause the drum motor to stop and
"OFF" will be displayed. Exiting the test will turn off the drum rotation.
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