Removal of plastic casing covering the black and grey tanks

[gbilger]

I have a 2001 Jayco Designer Legacy 5th wheel I bought used about 6 months ago. When I was parked for a month in Mesa, Az I would noticed that when the tanks got somewhat full that there was some dripping going underneath. It would go away after I emptied the tanks. I could not tell exactly where it was coming from as the black tank and the bath/shower grey tank are covered and protected by a plastic casing also covering the slide valves except for the handles. I'm guessing when the tanks are somewhat full and putting pressure on the slide valve seals, it is starting to drip. Just a guess. The actual slide valve for the kitchen (grey tank 2)is exposed and could be easily replaced. Has anyone ever dropped the 2 piece casing to expose those two tanks and slide valves. Also I can't get water through my sewer flush. It looks to me from the hose hookup it is a straight shot to the other side via the storage compartment. There is a inline shutoff near the other side but then it just 90's straight through the floor into I assume is the black tank. I called Jayco and waiting for a call back but the first answer I got from the gal was there a check valve near the shower. Doesn't make any sense. Like I said it is a straight from the hose connection across the trailer and down into the tank. Any thoughts on this anybody? Thanks in advance.