I have read every post regarding re-centering the worm housing with no luck. Replaced radiator and disconnected steering housing. After putting back together- self steers hard to left- raised wheels off ground, drained some fluid (used 10-40 motor oil due to leak that I want to find later) loosened housing bolts, started tractor and found point where it steered both directions w/ same force. When I tried to add back the fluid the steering went to the left hard again! Is it the motor oil? Is it another problem? When I drained the old fluid there was very little (1 cup) in the system. Is the power steering fluid measured while running? I really never have had actual power steering before. Thanks in advance for any guidance/advice.