Crud in the filter, huh?
I just had mine in to the dealer for its 50 hour before fall started. Prior to that is when I noticed it was having a hard time with the slight road grade in front of my house. I forgot to mention..., but I also could not cross my creek anymore in high range and with low rpms. I seem to remember being able to do this before when I first got the tractor.
At my 50 hour the dealer told me that there was crud in the fuel filter! /forums/images/graemlins/shocked.gif
I think it's worth it to warm her up and head up the road for a little test of my own. I will post back under this thread, but I also feel the ballasted tires may have something to do with the high range struggles, even without the HST pedal fully depressed.
I'm glad you found the problem, Ramon!