For all you folks already with the manuals, I've got a question. Over on the left side of the tractor, just below the starter motor is the Hydrostatic filter. Either in the piping coming to the filter, or in the gray head that the filter screws on to, I get a buzzing rattle sometimes. At first I thought it was the starter, but by putting my hand on the head and piping, I can also feel it. It's not always there and usually if just idling for a while, it goes away. Is there something in that head, like some type of diverter valve or ball and spring arraingment that could be rattling. I notice that about 4 lines actually come to that area, so I'm guessing some type of valving must be in there. I drove a 45D at a dealer last week and it made the same sound. Could it be air in the hydro lines? I love my tractor, but this sure sounds cheap and annoying. What do you make of this?