I have been working on this Taylor 336 replacing a Rusted out hopper with a reman. Now the mix cooling system quit working. The constant expansion valve has been replaced but it is either wide open or completely closed. When valve is closed the high side reads 150 psi and the low side has abouy 20 inches of vac. when closed and both are constant at 60 psi when adjusted open. It seems there is no adjustment.