I just bought Craftsman Lawn Tractor, Kohler 21HP, Model No. 917.27662, with the Automatic Transmission, (speed lever on the fender) I have a little over an hour use on it. When taking off and especially climbing any hilly terrain, there is a noise that sound like dry, soft rumble coming from the transaxle area. I believe it is the automatic or hydro transmission making this noise. Is this normal? It is loud enough that it bugs me, especially after just paying 1499.00 for it. Does anyone have experience with these hydro transmissions and know what I should or shouldn't be hearing?