adjusting the N75 valve will give a slight improvement but too far will kill it and it`s an irreversable adjustment. an 8th of a turn is all that it needs.. imo i wouldnt bother.
if it is the n75 valve you have broke, you can fix it by taking it apart, rewind the screw and push the solenoid back from the inside then you need to glue the T piece back. once you take it apart it may not work the same again.
