Yup, that would indicate the valve is still centered..... Did you see anything inside the front residual valve that looked like it could cause a malfunction when you had it apart??? If you have access to a pressure bleeder I think it would certainly be worth a try..... Have you ever put a gauge on the brake lines to see what pressure the M/C puts out? What bore size is the M/C????

Only other thing I could think of to try is to test the Booster with a vacuum gauge and make sure it is holding pressure???? Even though it is new, that doesn't always mean much these days..........