Waste gate not sealing

[Deleted member 2636]

I have a bulk waste water tank. It has a push/pull plastic gate valve. When I drop off grey water it never seems to seal properly.
Has anyone got any suggestions as to why or what one should do to make it seal? Should I replace the valve. It is probably ten years old by now.

 

[Deleted member 3011]

The seal usually has a V-shaped recess that the blade slides into and it could be there are some food scraps lodged in the recess. Carefully clean it out and lubricate with vaseline or similar. The lubrication also helps the lip of the seal rolling over when the blade enters and that causes leaks as well