To use the Mighty Vac disconnect the hoses frome the actuator. Draw a vacuum on both sides, one to go up, the other to go down. If that works one of the first things I would check is the solenoid. If it does not have key on/run power it will bleed off the vacuum. For test purposes bypass it. I would also test for vacuum at the switch which should be deriving it from the canister. If you have vacuum at the switch and it's not the solenoid test for vacuum at the switch nipples. If no vacuum or very weak it is a bad switch which may be able to be fixed.