We currently have 2 Jabsco electric toilets on our 1979 Bluewater Sports Sedan. This boat is new to us. They are both early model electric heads. We have discovered that both toilets have issues, seemingly requiring rebuild kits. They both appear to flush with "dirty" water on occasion, its supposed to be clean water. The Jabsco site tells me this is an indication of a bad main seal by the impellar We are wondering if it would be wise to invest in new heads. Has the technology improved enough over the last 20 years to justify new toilets over rebuilding these. I am leaning that way. I will replace all of the hoses to the holding tanks at the same time. Each head has its own holding tank, why is a mystery to me. I am thinking of plumbing both into a single larger holding tank, and increasing the size of the vent tubing. Currently, both holding tanks are interconnected with 1 inch tubing for venting......seems inadequate. What do you think?