Interesting that this showed up on the forum, went to the boat, sailing for 6 days came back tried the macerator.......
well, we are going out again for 10 days...so replacement is in order....
went to WM and bought JABSCO model 18590 self priming with run dry protection and installed it.
That was 2 exciting hours!
and it works!
Boat is a 2001 model-previous pump was original