My over the cab bunk on my class A THOR challenger GT starts to come down fine but then binds up on something on the passenger side. The drivers side continues to go down. When lowering bunk, it comes to a sudden stop on the passenger side 6 or 8 inches down from the roof. I then have to rock the bunk up and down (by using switch up and down) to get it level at the roof again. I can not see anything that is holding it up. Power and fuses all good, and no codes flashing on the Lippert control above the drivers seat. Ideas anyone?