I have a 753 that I believe may have a problem with one of the replenishing valves. I have a service manual but the pictures are not good and the info on the hydorstatic pump is limited. The pump is a Danfoss M91-35916R. As near as I can tell it looks like two of the valves are on top of the pump under the centering plate and it looks like the other two are on the bottom. Can any one tell me if that is correct? If it is correct, is there anyway to get to the valves on the bottom without pulling the pump? Do I have to pull the engine to remove the pump? Thanks in advance for any info!