Jerry,
Even if you could find parts to repair the automatic operation of your hydraulic leveling system, it is very doubtful that you could find a qualified repair technician in your area. Since I have no idea what you would have to pay for the parts, if you could find them, the only price estimate that I can give you to repair the hydraulic leveling system is the $1,200 that BCS (Beaver Coach Sales) charges to convert the system to a manual hydraulic leveling system.
As for your question about dumping the air before leveling, that is the procedure that is used when hydraulic leveling, but not if you are using air leveling. The air leveling system will lower the high point on the coach by letting air out of the suspension until it is level. It will only add air to level the coach if the coach high point will not come down any more, then it will add air to the low point. That is why it is important that the electric compressor for the air leveling system to be operational, because it supplies the necessary air pressure to maintain the level condition of the coach while you are camped.
Another thing to remember is to extend the slides before you level and retract them only after the suspension is completely inflated back to travel height. In other words "slides out first and in last".
Gerald