Unless your head is a Groco...
I'd say they were prob'ly shot a long time ago. And yes, they can be replaced. But you prob'ly need more than just the pump shaft o-rings...it's long past time for a complete rebuild kit. The toilet prob'ly hasn't seen any lubrication since it left the factory either....annual lubrication with a thick teflon grease such as SuperLube reduces seal wear considerably, and gives you an opportunity to inspect seals, valves etc and replace any that are worn while you have the pump apart. Depending upon the age of your toilet, and the price of the rebuild kit vs the price of an identical replacement toilet--you may be better off just replacing the toilet If it's a Jabsco, more than 5 years old, I wouldn't put any money into it...Five years is about the lifespan of a Jabsco manual toilet. And, it might be good idea if you read the articles in the Head Mistress forum Reference Library. Lotta good information there about how to maintain sanitation systems.
