I had a sticky seal for the first year or so on one of my three powered vents, which required shutting it off, letting the motor restore things to a sealed condition, and then trying again. Only once or twice did I have resort to manually turning the crank to break it loose.
The second season, the problem pretty much went away, as I suspect the seal weathered a bit from being exposed, and became less tacky.
2009 K-2500 Duramax
2014 Silverback 33RL