Sounds like a Groco...
They're notorious for spitting in your eye if the pump seals aren't replaced at least annually. The model is prob'ly an HF...or, if it's original, an HC or HE, which are the obsolete predecessors to the HF. No...all heads are not alike, and only the rebuild kit for a particular head will fit. Get out your West Marine BOAT/US or other catalog and compare yours carefully with the pictures of the heads in the catalog. If there's ANY difference, it's not the same head. If you can't find yours in any of the catalogs, I wouldn't spend any money on an obsolete toilet, I'd just replace it. Check to make sure your seacock wasn't closed...but I consider the squirting to be more important when it comes to making a decision whether to rebuild or replace. And don't be upset with your surveyor for missing the fact that it's squirting...the seller could very easily have put a little vegetable oil in it to free it up and hide its problems...which showed up again once it had a chance to dry out again.
