So my Dad bought a new airless paint sprayer (to replace this one) and I took the gun from the new one and put it on this old one and it fit the hose perfectly. Took it up to a neighbor's to try it out and it looked promising but it only had pressure for a few seconds then it would go away. I gave up and washed it out and realized the valve assembly was not tight to the pump (leaking water everywhere) and once i tightened that up and thinned the paint out a little It worked like a champ:fing32:. It was even making the hydraulic release knock the way it was supposed to. Not bad for having a bunch of paint dry in it and sitting for 20 years.