Originally Posted by mtnman
.....The handle will slide back and forth but nothing happens.
IF...the handle slides in and out with no resistance whatsoever - just the rod sliding back and forth -
the valve COULD be rebuilt.
Various camping supply stores carry "kits" for the Thetford valve rebuilds.
On the opposite side of the valve that the picture is taken there are two areas that the valve separates - the belly pan will have to be cut or dropped from this area.
Not a terribly hard job, but a terribly nasty one.
Check out this thread: