Bob, I'll mention a couple of things here if you don't find it to be a toe in problem like Rolf suggested. I don't have any R40s around me but I believe they have a single steering cylinder system instead of two cylinder system of R50 ect. The single cylinder system in much more prone to a wandering problem. I'd have someone sit in the seat and have them crank the wheel about a half turn one way and then back and repeat while I very carefully watch the tie rods to see which one has the looseness. It could be the nut on stud that holds tie rod to its anchor is loose so stud is wobbling in anchor. It could be anchor is wobbling in axle housing. Any looseness will cause a hard to control machine on the road. I have only seen one dual steering cylinder machine have a wandering problem and it was drinking something. No accually it was a R72 and the weld that holds cylinder anchor to spindle had cracked on both sides of machine. That allowed the wheels to wander around a bit on there own and caused a delayed reaction when tring to steer it. I suggested to the guy to quit taking corners at 10 mph with 330 bu. on board. Good luck finding your problem for she should take the road as straight as an arrow. Dan