I did end up using the new carb , thought a first I wasn't going to need it but ... I did not end up using the new unloader valve , it stalled the motor when I let off the trigger - probably adjusted for too high a relief pressure . The low pressure relief is disabled , I have to hold the trigger open for it to start . I'm going to see if I can source the correct parts , apparently a generic spring and ball ain't gonna cut it . I did change the relief pressure setting on the old unloader , backed the screw off one full turn and now the original unloader is functioning correctly . It too was stalling the motor when I released the trigger . Well , now I get to test the detergent supply and if that works I'm going to wash the car - but not today , we're still having afternoon thunderstorms . Be kinda like having my own little car wash out here in the woods .