There is a relatively easy (rollup) procedure (bit more difficult the first time to deploy) to manually use the awning provided you still have the "emergency strap" that should have been in a drawer in your camper
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The procedure is in the manual (attached).
THANKS TO FRANKM for the following!
This is from the Dometic Power Awning Manual,
In Case Of Coach Power Failure Or To Manually
This procedure will require two people (Minimum). When this procedure has been performed, the awning must be serviced by a Dometic Service Center or a qualified service technician before using again.
1. Slide the pull strap (provided) into the utility slot of the FRTA.
1a. Slide to middle of awning (Herk Edit)
2. While one person is holding onto the pull strap, remove the screw in the top of the right top casting.
The (Awning) will immediately roll in once the bolt is removed. Walk the awning to the closed position.
3. Align hole where screw was removed and replace screw into top casting to secure awning.
Screw must be re-installed to prevent awning from opening during travel. Have awning serviced by a Dometic Service Center or a qualified service technician before attempting to open awning after this procedure has been performed.
So, to TRY TO manually deploy the awning without power:
WARNING - you MUST have the STRAP to try this!
1) With TWO people (one on each end) MINIMUM (it will be easier with three) remove the screw on the motor side.
2) WALK the awning out against the spring torque (which will get stronger as you extend it!) by unwinding the roller from underneath. HANG ON as it is unrolled! If you let go it will retract under great pressure and you may get hurt (or damage the awning further).
3) When extended, HANG ON TO THE ROLLER AT BOTH ENDS
and have someone reinstall the screw.
4) INSTALL THE EMERGENCY RETRACTION STRAP AND SLIDE TO MIDDLE OF ROLLER.
Without the strap you will be UNABLE to safely retract the awning!
LEAVE THE STRAP IN PLACE UNTIL IT IS REPAIRED!