Find the solenoid, it will have 2 wires and 2 maybe 3 vacuum lines.
1 vacuum line will go to the intake, the vacuum source.
Then 1 vacuum line will go to a "T" with 1 hose to each actuator
Or, there will be 2 vacuum lines on the solenoid 1 for each actuator.
Solenoid is just a 12volt coil, when power is passed thru it, it opens/passes the vacuum from the intake to the actuators.
It doesn't have a + or -, just as long as one connection is + and the other - it should "click" and vacuum should pass thru it.
You can test it with a 9volt battery or car battery power, which ever is easier.
If you pull off the vacuum lines(mark them) and put your own hose on it, you can blow thru that hose as you power the solenoid, when it opens it should pass air then stop passing air with no power