I was replacing the original Motor Controller board (uncontrollable speed). The installation instructions were easy to follow. I suggest you get some small cable zip ties before you start. I had to clip a few cable ties to allow cable movement & used cable zip ties to rebundle the wires when finished. Calibrating the speed instructions didn't seem to work well. I could not get the speed between 9.7 & 10.3 mph using the speed potentiometer. Oh well, I don't walk that fast anyway. It seemed to be fine at 3 to 4 mph. I'll try the Owner's Manual (Pro Form CX 18i) calibration instructions next. It seems slightly different.