Rick, if it's not lowering electrically, you'll need to get the top off the safety bar and then someone will have to hold the safety bar retracted while you activate the manual release in front. It either turns (a knob) or it's a lever that you move backwards or forwards I think, but don't know which way.
IF, you've opened the valve already, it's dropped on the safety bar and is stuck there. You'll have to close the valve, raise the top off the bar. retract the bar and then, with the bar retracted, open the valve again. It will lower normally - it won't "crash" down.
Hope this helps.
- Jack