From what I read about your coach, the slide uses HWH hydraulic systems. (same as mine). It sounds like one of the hydraulic actuators has quit for what ever reason. (mine quit because of a broken line). The owners manual has a procedure for manually retracting the slide. It involves re-positioning a valve or two and then winching the slide in. No fun but it does work. I guess if the problem wasn't a hydraulic one but rather a mechanical failure of some sort, the manual procedure would not work either.
I'm very interested in what you come up with.
2004 Itasca Sunrise W22 chassis GM 8.1 Allison 1000 Towing a 2007 Chevy Cobalt four wheels down.