I'd just replace the entire toilet...
It's 10 years old, which is about the natural lifespan of any toilet...and Jabsco toilets seldom last that long. By now, even rebuilding it isn't likely to restore it to peak efficiency. You can buy an entire toilet at discount for just about the same as it will cost you to order a new motor/macerator--which will cost you list 'cuz it's a "special order" item, and is the most expensive part of the toilet--and a rebuild kit, plus it's a lot easier job...just remove two hoses, 4 bolts and the wiring, take the toilet out, set the new one in and reconnect every thing.And if you've been wishing you had a toilet that could draw off your fresh water system, you'll never have a better excuse to upgrade. Fresh water flush offers more advantages than just eliminating the sea water odor problems...they use a fraction of the flush water, a tiny fraction of the electrical current, and they're a WHOLE lot quieter. And a toilet with a fresh water solenoid option doesn't cost but very little more than one with a seawater pump. Whether you replace the whole toilet or just take it out to put in a new pump assembly, I'd fill the mounting holes and re-tap them so that the lag bolts get a good bite again and the toilet won't wobble. Give it some thought and do a little shopping before you commit to trying to salvage an antique.