We have a 1993 Flagstaff 621 tent trailer. I believe that this has a Jayco lift system. When trying to crank up the roof recently, the crank was only working partially - it would not fully lift the weight, so one person cranked while the other pushed up on the roof from inside. This eventually got the roof extended fully. Now the roof is stuck in the fully extended position and will not go down. I have tried using a pipe wrench with quite a bit of force to turn the crank in the down direction, but no luck. Any idea what could be causing it to be stuck? Thanks!