[wingnut60]

Ron,
Mine does the same thing--it seems to come from the plastic guide/bumper on the upper corner of the slide--it gets hooked behind the metal flange in the same corner of the trailer frame. I use silicone spray on the plastic guide when I think about it--no pop for several uses, then it comes back. Another spray, its gone again for a few uses.
Joe
I was at the factory last Sept--they went over all slide movements and no pop for several months, now its back again.

Check the upper corner of the trailer near the door--see if the metal is bent outward--that is where the plastic is hooking.