While poking around on the new tractor, I leaned my ankle against the front tire tread. I felt a klunk. Appeared to be some play in the front bushing. So I dropped the differential down to see what was worn. Two things went wrong. Only greased once, possibly when it was new, and somehow the weight of the tractor was resting on the bolt and pivoting. I am guessing the bolt was not tight enough to hold the long bushing between the frame members. The clearance is so tight you can barely force grease out between the long bushing and the two short bushings in the differential housing. I filled the cavity and forced grease between the bushings before lifting it back into the frame. The trick is getting the bushing centered so when you tighten the bolt, there is no contact of the bolt and long bushing. This forces the weight to be carried by the bushings. I think I got it.
Bolt and long bushing