We had a similar thing in our Country Coach. Turned out to be a very small plastic piece (about 3 X 3") that had worn off and caused the problem. It started for us with a clunk and a lot of noise, but it went in and out. We didn't do anything until, leaving a park, it never quite went all the way in. They had to open the slide, jack it up a little, replace the small plastic part (I'm sure it has a real name!) and let the slide down. The whole repair took a few hours with two people working. Thankfully, one was my husband and his labor is free.