I'm finally getting aroud to fixing the cylinder on the henderson loader on my farmall m. I've got to get this fixed so I can pick up round bales. There is a square aluminum block at the top of the cylinder with a hole( I'm assuming this is an air vent) oil currently pours out of this hole when the loader comes up at all. I took off the four nuts that hold the block on and pulled the shaft out. Now I don't know how to fix this. I thought there would be an obvious o-ring or some sort of seal. There is a nut on the bottom of the shaft I haven't removed yet. How do I fix this? Thanks