There are rollers and on that particular model, jacks and slides are HWH hydraulic - it's the same model and year we had. When that slide is extended, most of the slide parts are visible. The plastic slide runners (not sure what kind of plastic/nylon/whatever they are) can crack so they should be an annual or biannual inspection item.Most large slides have rollers under them. If a roller is not working or is gummed up, the slide will not perform correctly. On my roller, the face was broken (plastic coating) for example.
Is your slide hydraulic? I believe it is. Could be a plumbing issue (plugged, weak pump, etc...)
2005 Itasca Horizon with HWH 625 slide. The large driver side slide is getting to the point it will barely retract. Other slides and levelers work. Shuttle valve or something else? Thanks for your input.