Is it a Schwintek slide? Have you tried to re-set it? There is a video online about how to do that. If you cannot find the video, I will look for it and post it.
We had issues with our Schwintek slide last month and it turned out they never sealed the slide properly when the trailer was built and water got in, destroying all kinds of stuff including the bed and the mechanism. We got it all fixed at the factory earlier this month. They practically re-built the entire slide.
2012 Cruiser Sahara 330SS
2015 F250 Super Duty diesel