When I hooked up the spare servo it also drove immediately to what must be full cool because the water path thru it is blocked. The fan speeds aren't the same (only high speed, no slow to high ramp up) I just am not seeing what is causing it to fully close & keep it there regardless of thumbwheel adjustment. It would be great to drive the servo open to get heat, but with this going on how can I get it to drive in the other direction?