Old camp, you can either undo a couple of the screws that hold the skirt in place where it is sagging, and look to see if the straps are attached or have your dealer do it for you. If the straps are not connected contact Shane Imus or Daniel Collins at PT and they'll take care of you. Good people and easy to work with.
We have an almost two year old 3400 and have never had an issue with our holding tank...until yesterday. We decided to get away for the weekend and camp nearby. Because it was going to be below freezing I decided to add some water to the tank in case we needed water in the middle of the night while the hose was disconnected. Started to fill the tank while setting up and heard an awful sound. After about 5 minutes of filling, the tank had pushed down the cover on the frame and the straps appear to be on the sides of the tank rather than under it. We are hose campers and rarely use the fresh water tank. At most I will leave a little in the tank when we go on long trips in case we use the bathroom on the road. The tank was empty prior to today since it had been winterized. Looks like I am off to the dealer and cutting our trip short!