donn0128 wrote:
Take it apart, and clean the TP off the blade and seals is the only real solution. Best to dump the black tank, then flush with lots of water until there is no more brown stuff coming out. Get a bucket, crawl under and take it apart. You will find two seals, one on each side of the blade. Clean everything up, and using lots of plumbers grease grease everything up and reassemble. Test for leaks with lots of clear water. If no leaks, then drain and use as normal.
If you're going to go this far, you may as well just buy a new valve and replace it instead of putting the old valve and seals back in. It's an easy job.
Bruce