I assume it is rolling on vinyl flooring like I have. And it sounds like maybe weight might be the problem. Can you see if the roller is sitting level on the floor when it is out?
Also, you probably have at least one other roller under that slide. Can you see if it is sitting level also?
When I had slide roller problems, my roller had come loose from the metal thing that was holding it in place. I had to leave my slide in until I could get a new roller and have the factory service place in Oregon replace it.
Also, it would be a big help if you would list the year, model, and maker of your rig at the bottom of your messages, as many of us have done. That way, maybe someone with the same rig can answer with better information than the rest of us have.