I have a 2006 L3830 with a BH90 backhoe. I bought it used with 600hrs. Everything worked great. Upon purchase I added a grapple to move logs on my woodlot. I plumbed it into the rear remote and run the hoses forward. Within hours the right rear stabilizer of the backhoe began going down by itself while I was using the grapple. Eventually the stabilizer lever locked and could not be moved. Beyond that the other valves in the bank began to leak. I disconnected the hoe and chained up the stabilizers. Over the last winter I replaced the o-rings in the valves and reassembled the unit. The backhoe seemed to work well and once again this summer I set out to use the grapple with the backhoe hooked up and on the tractor. Within hours I could hear fluid moving behind me and once again the stabilizer lever locked. This time it was the other one (left). Now three of the valves are again leaking and I have had to disconnect the backhoe which is essentially useless. I have spoken to several dealers and nobody seems to know what is going on. In addition, there are several postings on the internet that describe the same problem. Nobody seems to have a solution. One poster suggested that back pressure from the grapple was blowing out the backhoe valve seals. Does anyone have any ideas as to why I am experiencing these issues? The rest of the tractor works fine and there are no leaks. Beyond all of this, Kubota wants $682 for one set of o-rings for the valves.