I seem to rememeber the 43 series was bad for for leaks in those tubes you talked of that run from side to side right between the motor and pump , there is about 4 of them and they rub together or against the frame , you have to take the motor out to get some of them in and out , the easy way would be to route a hydraulic hose in place of the tubing once you figure out if that is it and which one , the thing to do like Tazza said is a real good cleaning so that you can see where it's coming from , the pump seal is kinda rare to see go out , it may also be leaking from one of the fitting orings on the side of the sunstrand and leaking down the side to the bottom and fooling you