How does it sound and act?
If bad check(stuck open) car will lift when switch is held and drop as soon as switch is released. If cloged motor will stress and car wil lift slow or not at all.
If bad dump (Stuck open) motor will spin effortlessly and stop slowly while oil cycles back to the tank
If low on oil you will get some lift and hear a gurgling/grinding noise.Totally dry motor will spin free with some whining from gears
If broke key. motor will have high pitch whine with some grinding from broken key debris and motor will stop slowly
If bad pump seal car may lift slowly or not at all but will sound as though pump has pressure. The motor will stop quickly as there is still some resistance from pressure.
Its better to learn how to reckognize the problems by the sound. That way you can go right to the problem.Or at least know where to start.