68 dart gt convertable wont go up?

My recollection is that it is a closed system and the fluid to lower the top is shifted from below the cylinders to above the cylinders so If it goes one way it should go the other. There are two check balls in the pump and perhaps one is not sealing properly. I'm sorry I don't know the fill procedure but i do have a shop manual at home and if no one answers you before I get home Ill look it up and the trouble shooting part too.

By the way has the system been re-tubed or removed and reinstalled?
when you put it up ( manually I assume) does it go up easily - no binding?, has the wiring been touched?
when the switch is pushed to raise does the pump strain or sound different than it does when it is lowered.