I have a Dometic and and I have to be easy when I press down to fill with water. There is a fine line before the flush ball opens and the water drains. Try pushing down very slowly and see if you get to a point that water flows in and the flush ball is still closed.
If after you get water in the tank it drains out the. You have a seal problem at the flush ball...
2016 Siverback 33IK
2015 Ford F-250 Lariat 6.7L V8 Diesel 4WD Super Cab
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