I have a 2013 Sunstar 26HE with MCD American Solo manual shades. My wife pulled on one of the shades, heard a "pop", and the shade unraveled toward the floor. The shade would no longer retract.
Thinking the tension spring broke inside the shade mechanism, I called MCD shade and spoke with "Bill". Bill had me take the shade apart. To my surprise the spring was intact. He then had me focus on a small black wheel that has a couple tabs on it. These tabs were suppose to be approximately 1/16" in height, but I could barely feel them with my finger. These tabs are suppose to keep tension on the spring. Bill told me movement from the motorhome, along with the tension of the spring, can cause this black piece to unwind. When the black piece unwinds, the force will cause the black tabs to shave off inside the shade mechanism and no longer hold tension on the spring.
After ordering the replacement parts, Bill told me a temporary fix was to take a soldering iron and burn several indents on the black piece. These indents will raise the plastic enough to hold the black piece in place and keep tension on the spring. Although skeptical, I tried this and it did work. The shade is in place while the replacement parts are being shipped to me.
Just something to think about should you run into the same problem.
John