If it is the same issue as ours, you will need to get a little dirty and clean the gasket and slot, that is in the actual toilet where it goes into the tank. That domed plate that the foot pedal operates to open or close, gets DIRTY and it hinders the return. To clean it there are video's that recommend using a coat hanger to get the crud out, DW uses a clothes pin end (with latex gloves), then sprays it with silicone spray.
Problem resolved! Works like new again!!
Has to be done every few months.
2013 Jayco Eagle 284BHS
250Watt Grape Solar Panel, MorningStar MPPT 60 Charge Controller
1500 Watt Ramsond PSI, 2 Trojan T145 Batteries (260Ah)
2 - AirSight Wireless IP Cameras (used as rear view cameras)
EnGenius WI-FI extender, D-Link wireless (n) modem
MagicJack Internet Phone
2012 Ford F150XLT, EcoBoost w/3.73
157" Wheel base, HD Towing Package
Our Solar Album http://www.jaycoowners.com/album.php?albumid=329