Just got a new TS 146XK and have 2 hours of run time on it and i have noticed if run around in forward or reverse at times it makes a whirling sound from the transmission or at least it seems to be from there. It has a hydrostatic transmission and i have never had a tractor with that type of tranny. The old Sears Craftsman finally bit the duct after 25+ years of use and abuse and it had a transaxel type tranny. Who knows maybe it is supposed to sound that way. ????