Here is my situation, I have new actuators vacuum hoses and a bushing kit installed in the head light doors. The head light doors do close slowly with 10" of vacuum. The head light doors also will open but only if I help them for 3/4's of the way, and there is only 6" of vacuum for the open circuit. Any ideas on the difference in vacuum between the open and closed circuits? It appears as 10" of vacuum is the minimum required to make the actuators work. Additionally I do not believe the vacuum tank is holding vacuum. I tested it and there are no leaks in it, should I put a check valve between the manifold feed line and the tank? Thanks for any replies.