What you have described is an underbody hoist with a piston cylinder where oil is displaced from the top end of the cylinder and pumped into the bottom. Upon lowering it the oil flow simply reverses. There is no pressure on the gear shaft unless there is slippage past the gears which indicates the bronze faced wear plates are worn. Otherwise (and if your lucky) you might have rotational wear on the seal itself and that is easily replaced. So you could have a minor problem or perhaps a more serious problem if the pump needs to be rebuilt or worse replaced. The thing that makes it expensive is that the valve was cast into the pump body on most brands so your looking at a pump and valve assembly, not just a less costly pump only replacement. See if you can determine the brand of the hoist, that will help with repair parts which are becoming harder to find these days.
