I have a JD 4210 that I purchase on 4/1/05 that developed an oil leak in the hydraulic cooler. It seems the battery leaked and caused the problem. The plate under the battery is very corroded and the cooler has corrosion all across the area where the battery sits. The hole is about the center of the cooler and just below the top of the battery. I contacted the dealer where I purchased the tractor and was told there is nothing they could do under warranty since it is 31 months old even though it has only 81.8 hours. I ordered a replacement and then started checking posts on TBN. It seems there are quite a few instances of this problem documented here. I read one that says there was a change in the type of battery from a manifold type to one with 6 screw down caps. My battery has the 6 caps and is part number LVA11725. They were tight and the fluid level is actually a little low, so I don't know how it leaked. There doesn't seem to be any damage to the battery case either.