What I do with mine is when I have the tank empty, I will remove all fittings so I can have access to the valve gate inside the pipe and shoot it with silicone spray and work the gate back and forth a few times. Sometimes I will find tp stuck to the grooves the gate fits in and will remove that prior to spraying the silicone. Works for me.
Ron
Ron & Sandie
2013 Tiffin Phaeton 42LH Cummins ISL 400hp
Toad: 2011 GMC Terrain SLT2
Tow Bar: Sterling AT
Toad Brakes: Unified by U.S. Gear
TPMS: Pressure Pro
Member of: GS, FMCA, Allegro
RETIRED!! How sweet it is....