I already replaced my original delvan pump a few years ago with a Remco. Now this Remco will not pump out of all four spray tip at one time. The pump will only spray out of one tip at a time. Also noticed the pressure dropping off to nothing when using the gun. I backed the pressure all the way off with the adjust dial and then turned the pressure back up which temporarily mitigated the issue with the gun. Is there something I can service on the pump? Or is the pump shot?