I had two of them do this on my Flagstaff (same as Rockwood) I tracked the problem to the nylon glides that they run on. They are pretty thin and if the screws are slightly crooked, the screw heads eat into the plastic pieces on the slide.
I addressed the issue by removing the nylon glides, on the main floor with thicker ones. I used pieces cut from a thocker plastic cutting board and countersunk the screws deeper.
Then I removed the plastic runners from the slide. O fabricated new ones from aluminum channel being carful to fold the ends like the original. This has worked perfectly for a few years.