I have an older MH with a single 14' slide. When I arrived at the MH today, I noticed that the slide had partially opened (and yes, I had the safeties on...it literally pulled one out of the floor). ...
On mine there are two solenoids, one to push the slide open and one to pull the slide shut. When one fails it allows the other to override it. Check your slide fluid level first, then check to see if you have two solenoids...switch them if you do and see if it retracts....good luck...Dennis