Mid '80's 843 with over 6000hrs, very little history came with the rig but I bought it cheap! During the few hours I've used it, there has been a "hammering" on the lower left side, kind of like an impact wrench sound. The left side has finally died as I get no power fore/aft when moving the stick (all controls/linkages appear to be fine). I suspected the drive motor on that side, pulled it off and had a buddy who owns a hyd shop check it out. Its fine. Now that leaves me with chain/sprockets/reduction gear? What do I check next? Questions: if pulling the chains and sprockets, do I also do axle seals/bearings at the same time? Is it just as easy to drop the entire under carriage/chassis to do this? What can go wrong in the reduction gear? What is the approx cost and time involved to do this myself? Where (dealer only?) do I get new sprockets/chain/bearings/seals? Thanks in advance for advice on my new winter project! Lance