The jacks occasionally lose their prime. This may occur as a result of prolonged periods of inactivity, excessive heat or cold, intense vibration, or vertical storage. This can be easily fixed.Turn the handle counterclockwise as you would if you were lowering the jack. Then pump the handle 10-12 times with full strokes.This will prime the system and push out any trapped air. Tighten the handle by turning it clockwise and it should work just fine.