It is a very common problem. It is just dirty! You can use w-d 40 but it is not to hard to take it apart and really clean it. Just be carefull it is spring loaded and the spring could jump out and could get lost. The cover is not even needed for the function of the fwd. It is just a safety feature. I have not heard of anyone breaking the cover by forcing it back so you can return to 2-wd to get back to the trailer after a ride.