This is an old Carefree problem. The awning roller is driven by the large black cap on the motor end of the awning. The cap gets its rotation from the shaft which slides through it. The cap is aluminum and the shaft is steel, with a single flat spot to drive the cap. Guess which wears out? The later motor assembly had a shaft with 2 flat spots and does provide better drive. The caps on each end of the tube are identical and can be interchanged. Doable but a pain to access. Research other RV forums and you will find some individuals have either pined the shaft to the end cap or were able to use a set screw to accomplish the same. For a period of time a few years ago, if you provided Carefree with some info or pix they would send a new motor assembly free of charge. I still carry my new one because I had swapped end caps and and did not want to do a cap replacement a second time. But I am sure my time will come.
Dennis Codella
2007 Endeavor 40PDQ