I have an 06 scag turf tiger 61" with a 27 hp kohler. The problem is the right side wheel motor seems to be getting week. It seems to start out ok but after a few hours (I assume after its hotter) it wont pull the same hills I know it did this summer. This machine only has about 70 or 80 hours on it. could it be some sort of valve or adjustment or am I in trouble here? Thanks in advance for any advice.