Hello! Not familiar with that C at all but does your slide out have a metal track on each end of the slide out box near the top? If so, you have a Schwintek slide mechanism and one motor is either out of sync with the other or has died.
Schwintek motors run between $75 - $225 depending on model at cost for the part. Replacement is easy enough for a tech physically, and then just needs to re-sync them so figure between 1 and 2 hours of labor from a dealer.