If at all possible I would take the motorhome to Forest City to get the repairs done at the factory service center. We had them repair our full wall slide last year. It was done as a "Goodwill Adjustment".
While the dealer may be able to replace the broken parts I doubt they have the equipment and expertise to properly repair the problem. Your case sounds similar to ours except in our case it was the lower front corner that would never stay in time.
At the factory service center they totally removed the slide. This means disconnecting all plumbing, gas and electrical connections as well as the slide mechanisms. They used a large padded fork truck to remove the slide itself and set it on custom made stands to do the repair work.
They replaced the motors and gear mechanisms at both ends, replaced the racks on the slide, added another roller under the kitchen island (to minimize the cantilevered weight, and removed the last body mounted roller at the bedroom end.
In our case the slide was not square with the body. It was high at the rear causing excessive pressure on the top front rack mechanism and very little gear engagement on the lower front gear mechanism.
We left the motorhome at the factory service center over the Thanksgiving week, and picked it up the following week. We're now In the middle of a one month trip. So far the slide has worked better than it did when the motorhome was new. The factory technicians did excellent work in a timely manner.
Hikerdogs
2013 Winnebago Adventurer
