The actuators tend to leak internally. Some will open and not close, some will close but not open. There is a seal inside around a piston that slides back and forth. They also can leak where the push rod comes out. A hand vacuum guage hooked to the acutator will help you find the leak. Just manually pump it and listen for air and also you can put your finger over the oposite hose connection on the actuator and if it builds vacuum but won't if you finger is off, then the piston is leaking.
68 RS, Ash Gold,pwr brakes,pwr windows,Hounds tooth,355/T350,3200 stall Dynamic converter,3.31:1 posi,Autometer guage pod