Jabsco head

[richard fry]

Jabsco manual head will not pump up fresh water to bowle it has a new joker valve installed in the past this has fixed it but this time it did not .Ive primed it and also shut water valve halve of it seamed fine but an hr later it lost its prime I can not see any thing wrong with the pump parts i know it does not cost much to replace it but i should be able to fix it any ideas thanks in advance