Welcome to the forum. Instructions for teardown on a 104 should be able to be found online if you do a Google search (models 100, 101, 102 and 104 are essentially all the same with some minor differences). I believe you can likely find most of the o-rings to re-seal it at a good industrial suppler- but the pump cup/seal I am not sure of which style it uses- it could be the difficult part.