Just wondering if anybody on here has experience repairing a steering hand pump on a 4430 jd tractor. They are a fairly complex set up. We are working on one that will lock up when you turn they wheel quickly one way. You also will constantly have to correct it when driving down the road as if oil is leaking by some where and allowing it to steer without operator input. We have already disassembled the hand pump once and replaced all seals but it did not seem to improve. Any body have any ideas ? Thanks.