verify  your  'lock'  isn't  engaged on the   3 pt!
But it's  probably  a  stuck  spool valve like  Valhalla   suggests.  

I got pretty handy at   snapping that linkage through the access hole and  freeing it up..   and when that didn't work:  jacking up the rear of the lift cover  just enough to remove the spool 
valve/cartridge  to clean it. 
    

Trick here is-     every day you run that tractor,   cycle the  3 point  a  few times!   
   One  guy  even  suggested to lock the arms up,  and lower the  quadrant so  the spool isn't  always  sitting in 'hold'  position.          

I  rebuilt my 1155's  steering  shaft,    the amount of  garbage that collects in that  case is  amazing..  it's like the  collection point for the whole system.

I had  them  build up the shaft  at the  bushing areas,  and  turn it down to spec.     It's really not too bad a  project.