Texar, that is not normal on the 3016. Test this at a dealers lot; put a load into the bucket of a new 3016 and see if the power-steering works. It will work. We do see this issue on some of the 10 series (now the 2500 series) with a loaded bucket if the surface is such that the tires are really gripping. And on those, it is just the nature of the beast. They put big tires on the front of some of these tractors, bigger I suspect than the "power steering engineer" anticipated. Move the tractor a 1/2" and the steering works fine. The dealer may be thinking about those models. But I've never seen that issue on a Mitsu built 15/16 series. If the dealer replaced the steering motor, that leaves the following possibilities: 1) Low hydraulic pressure. 2) Steering hydraulic cylinder bypassing some oil, causing it to be weak. 3) Some sort of binding in the knuckles causing hard steering. Of these three, #1 is easy to test. #3 is super unlikely. #2 would be my guess. Perhaps when the cylinder was manufactured the ring on the piston got scuffed and now has a gouge in it.
Those are my guesses, please let us know.