I have a 643 and am having some problems with it. I need some help.... 1. when i am running the bobcat at full throttle, engine dies down to almost stall. I let go of everything and the engine slowly comes back up to full throttle. 2. The bucket and boom are creeping down quickly with the engine off or on. 3. When I start the engine, if the brake isn't on, the bobcat starts moving backwards. The hydrostatic drive appears to be in reverse. 4. The bobcat will not start without ether. (could this be because the hydrostatic drive is engaged in reverse?) Is it possible that a valve that is bypassing could cause these problems. Any help or suggestions would be greatly appreciated. The bobcat is in excellent shape with only 1300 hrs. It is a 91. I have had this problem since i bought the machine 2 years ago. It's now in the heated garage and i am going to change all my filters and put in new glow plugs. I'd like to try to solve the above issues before the snow starts to fly. Thanks