Does it only leak when you have driven it with the tanks full, or does it leak when you are filling it? Will it leak if you fill it and it is just sitting still? How much does it lower your tanks? Does the leak drain them?
There have been a few issues with the vent tube being cracked, broken or fallen off, as well as the connections where it goes into the tank. Also if you have 2 fresh water (45 gallon)tanks the connection hose between the two could have cracked or come loose. In order to know for sure you will probably have to drop the chloroplast off the bottom of the coach and look for the leak.
Hope this helps. Happy hunting!
Rod Ditrich