I have a Kubota D722 engine, got some air into the system while changing fuel filter. Bled the system up to the injection pump, could only get one injector to put out fuel...Took pump out and apart. Soaked all the parts. Put it back together with, surprise, same result...one injector emitting fuel, the other two dry...The pump and parts "look" fine. Clean, no signs of wear or corrosion...The springs seem very strong feeling...Not sure what to do next. Any ideas would be much appreciated. Thanks. TK