To test the actuator connect your hand vacuum pump to it and pump up a vacuum of 10 to 15Hg. Note that on this early style actuator there are two connections for vacuum; however, only one is used. The actuator is reversible for mounting on the driver's side of the car. If you connect it and you are unable to pull any vacuum try switching them.

Watch for a vacuum leak. On this actuator there was a very slow leak of about 1Hg a minute. This explains why the system, which had been checked and fixed of all other leaks, was still leaking down overnight.