Don't know much on the history or the tractor other that the guy bought it about a year ago and he said the steering relief always hissed, but the hydraulics still work.  Untill this spring when he started having problems with it lifting anything. 3pt and remotes.  There is no loader on the tractor. First thing I check was the pressures, of course, and the steering relief pressure was way low.  Shimmed it up so much ended up changing the spring which got the pressure back up.  Did some looking at the steering gear and someone did change it out.  According to manual and serial number it should have the Saginaw Hydramotor but what's in there now looks like a Char-Lynn unit in plumbing setup anyways.  Looks plumbed correctly.  P is the pressure coming in, L goes to the left side, R to right, and T goes back to the tank/reservoir.  Will an open center steering gear help get pressure to go to the remotes and everywhere else?  I understand that it will fix the issue of blowing by the steering relief.