They changed not only the valve stem - but also the valve body slightly. Please call CCM and have both sent to you. Make sure you have the pressure set at 350 psi - and I would toss in a set of springs to make sure you valve spring is not too weak.
That makes sense to me. It would not be dumb to call Rod and have him talk you through what you have tried. He is great about knowing little things that I can't think of or have had experience with. Rod is one of the best listeners concerning tech issues I know of.
Good for you for being open and honest and selling a good marker.