Review on Thetford 34100 Style Water Valve by Dante Jeppi

I replaced my leaking valve with a brand new one and within a week it started leaking again so I put it back in for another new valve which leaked straight away. The stuffing box seal was noticeably deformed and squeezed out of the valve body. I don't want to order another one but the leak is starting to ruin my sub so I guess I have no choice but this is a terrible design. I wish there was an alternative or third party manufacturer that offered a superior product. I've tried applying silicone to each seam, but the water still somehow comes through. Thetford makes great toilets, but they should be ashamed of their terrible design. Every forum I've looked at even says it's a frequently replaced valve - something you should replace annually. That's ridiculous.