Finally found the name of the plastic. Did a search for "rv belly liner" and got the name Coroplast. Got that at Home Depot and cut a patch. Use sm screws to attach like one from the factory that was already under there. The motor was much further back than I had imagined, had an extension that was longer I thought. Thanks for the tape idea, edge of the tape I had did not stick well. Not sure what a Schwintek is, thought that one was in the wall. Mine is underneath. Watch for sand falling in you face when you cut the hole and open it up. Changing the motor, piece of cake. One bolt holds it in is all I saw.
2013 Flagstaff 831FKBSS