Thank you jdc1, Jim&Carolyn, MitchF150 and bdpreece,
I appreciate your comments and have booked the earliest appointment for replacement on Oct 12th. We only turned 50,000 miles on this last trip and try to keep our RT in the best condition we can...even no tissue in the black tank! This will be my second replacement macerator! A little disappointing for so little use, but maybe that is part of the problem.
Hopefully I can figure out some way to empty the tank before taking it to the RV Centre so they don't have to endure that unpleasantry!
Thanks again for your input.