Not sure if its the same problem OP is having but when closing mine the aft side would stop retracting but the forward side would keep going until the whole thing would bind and stop. Took several out and in tries to get it to come all the way in. Took it to the dealer who talked with Schwintek and their answer is that it must be very level in order to move smoothly; they sugested leveling with the jacks before each operation. Apparently there is enough flex in the camper body that it puts stress on the slide rails if not level.
I'll try to get it as level as I can with my small bubble level before fully extending. When just needing quick acccess I'll just open enough to squezze in rather than opening fully. Hopefully that will keep things working...
2016 EC 960; 2016 RAM 3500 DRW CTD; Superhitch w/42" Ext; 2006 Jeep LJ Rubicon w/16' carhauler