I'd recommend rebuilding the whole pump
, if you're going to take it apart, and also do a thorough cleaning
to remove all the calcium buildup that's likely in there too. There's a great YouTube video of this guy taking Raritan
apart. He never says a word. Only shows his hands, the pump, the tools and the parts
. It's a most excellent tutorial to have on replay while you're doing this. It's also a dirty job but it'll give you a huge sense of accomplishment afterward.