I have a Toro 30 Timemaster purchased in 2019. I have replaced all belts mower blade spindle's, tightened to cable for blade engagement. New carburetor, air filter. It will not cut thru thick grass without bogging down. Blades have been sharpened.. It used to pull me up hills, now I need to push it like it has no traction. What can I do to get the power back ????