i only have power tilt.For two years it has worked but would slowly leak back to down position.I was advised it was expensive,so I made do.Today I went out and there was oil on my transom,apparently from the cylinder bolted there.There are hydraulic lines going to it.Halfway down this cylider is what appears to be a fill hole with a knob that twists off.This is a force 50.What type of fluid does it take?Where do I fill it?what do you think is wrong?All help is appreciated.James