There are Teflon blocks the slide rides on along the under side on the bottom of the opening. Seen when slide is out from the outside under the slide edge. I think there are three. They can come loose and fold over or fall out.
If that is not the issue, there is an adjustment under the bed, the large nut on the end of the rod from the actuator, it adjusts the distance the slide comes in at the bottom. This may be where you need to look.
Bill
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