Check the voltage...
Sluggish operation often means low voltage to the toilet. It can be due to a variety of causes--bad battery, corroded wires, corroded terminals, head is too far from the battery, wrong wire size AND too much distance. However, any of these problems will also cause the toilet discharge to be sluggish too, it doesn't only affect flush water intake. Other possibilities--more likely if the toilet flushes ok, just doesn't want to bring in flush water: the toilet intake line is clogged with sea water calcium carbonates or organic matter that's been sucked up into it...animal or vegetable sea life has overgrown the thru-hull, partially or completely blocking it...there's an air leak or damage in the intake line somewhere that's preventing the toilet from priming--it could be as simple as a loose hose clamp at the thru-hull, or sand, grit or other debris has damaged (scratched, scored) the impeller housing, preventing the impellers from working efficiently--and when that happens, it also damages impellers...a new one will work for about a minute before it fails. Do you have an owners manual? If so, have you checked it to see what it says the possible causes and cures are? If you don't have one, I suggest you get one...'cuz you can waste a lot of time effort and money taking wild guesses and replacing the wrong parts. If this particular problem isn't covered in the owners manual, and none of my suspicions are true either, contact Jabsco.
