I've got a 13x74 that has done that since new. When you raise it up after it has settled does it blow oil out that vent? I figured it was the o-ring on the piston but after looking at it decided it was easier to hit the raise lever everyday when it is up instead of trying to wrestle with a cylinder that looks to weigh 3 or 4 hundred pounds. 

I have a 10x81 Westfield also that has a two way cylinder. It can't settle because of this problem because it already has oil on both sides of the cylinder. I'm wondering if the one ways can be converted to a two way?