Are you trying to make it easier to steer? If so, then adjustment of the steering gear box (or repairs if necessary) might help. Be sure the front axle kingpins are greased, and, if you want, you can add the bearing on the steering gear box. part way down on this page:
http://ccspecialties.org/steering_seats.html. That seems to help some. Also, the tires you have can make a big difference in ease of steering. I don't know about power steering, somebody else will have to jump in on that. I have a 1650 as well. Nice tractor.