I have an older JD 644b and I'm having problems pushing through a pile of dirt to get a full load in the bucket. I'm changing fuel filters here soon, but it seems like it just doesn't have enough power to push through. Doesn't seem like the engine is choking or bogging down, just not enough power with the wheel to get through the dirt. Seems to lift and turn just fine.
Hmmmmm does it feel like it is in 2nd gear?
Did you check to make sure it's not low on transmission fluid?
I'll check tonight... Thanks for the thought
Theres several throttle linkage pivots that wear out all at the same time resulting in less than max engine RPM, which creates doggy transmission response. With the pedal to the stop on the floor, make sure the injection pump lever is against the stop on the pump --- If not, sometimes a slight upward bend (very stretched out upside down V) in that final long linkage rod can take up some of the slack created by loose pivot points.