So did you also plug the lines at both hubs simultaneously in case they are both leaking? If you only did one at a time you didn't rule that out. Then, if you did that and still had a leak did you plug the PVH solenoid on the hub side, where vacuum leaves the PVH and goes to the hubs? That would prove the PVH good or bad. In my case both hubs were leaking and the solenoid was bad as well. Sometimes the solenoid body actually can crack and leak. The PVH solenoid does not provide a steady vacuum, it provides a "pulsed" vacuum.