jjnj (Joan) - If your jacks are slowly loosening and falling, that may be a clue. Our jacks have a rubber pad and stick rather nicely in place if they are clean. I do not have to tighten them too much. I might speculate that there is a slight twist between the coach body and the slide body. The shifting of the mismatch would relax the tension and the jacks would slowly fall. You would need to tighten enough to twist the slide to match the body to avoid the jacks from becoming loosened.
Will be interesting if R-Vision is coming out. Your dealer must have some clout.
TonyTiger also has a very good point. Just because the water enters the coach near the slide does not mean that the slide is the culprit. But, in your case I know you said that the problem changes when the slide is in or out. So...it certainly sounds like the problem.
Gene
Model 211-S with 5.7 Chevy