Since I first posted, I fixed the ones that broke, Put some sealer around the remaining screw heads. Haven't had any more heads pop. I had some screws on the fender plastic skirts back out, I also put some sealer on the screws and tightened them back up, seems to be holding them tight.
On the exterior of our bedroom slide floor, I have never been able to completely keep it from getting wet with some rain storms. Water will run down the lower schwintek gear tracks, then wick into the exterior bottom side of the bedroom floor. Doesn't happen often but with some storms / rain showers, it does get wet.