Not sure about the pressure buildup. I could see oil dripping out of the seal sitting still after driving it into my shop. I decided to pull it down while I had the time to check it out. After getting the hub off I decided to take it to my dealer because I don't have a press in my shop yet. After talking to the shop foreman I found out they average about 1 tractor a week with these same seal problems. He said they find wire, baling twine, sticks, small rocks and other assorted objects tearing in to these seals. They had it apart in 10 minutes and back together in less than 30 minutes. The only thing that hurt was the seal was around 50 dollars. Total repair ran about 130 dollars with a gallon of Hy-gard and a tube of silicone. Good thing I took it apart myself or I would have been out another 100 bucks in labor. Seems a little excessive for a simple repair. I am sure John Deere is aware of this problem and it looks like an engineer could come up with a possible fix. Oh well I guess that's what keeps the service department in business. Sorry for the rant but sometimes I feel like I can't fix things as fast as they break.