One valve controls the lowering and the other the raising (retracting). Screw the needle valve in to slow it down, out to speed it up. For the leak, I suggest powering it up (air) and going over each connection with a soapy water mix looking for bubbles. Another way is to use a piece of fuel tubing - one end close to your ear and the other at each connection - and listen for air escaping. This can be done with a tubing extension aimed at the connections (closely) to get to hard to get to places.