1997 John Deere 648G Steering Issue

[spinner]

Looking at buying a '97 deere 648G, run really good, hydraulics seemed strong, raised and lowered blade, dual arch and grapple seemed fine, could lift machine at an idle.
But when went to turn Skidder it would only move a little bit in each direction than stop, could kinda feel in steering wheel like it was starving for oil , oil level is fine. What could be wrong ? Is there only one main hydraulic pump in unit or is there a steering pump also ? Any help would be greatly appreciated. Thanks. 

[Maine logger88]

Were you driving and turning or just turning sitting still? Also if the diff lock is on and you try to steer then it will do that especially sitting still

[spinner]

Was sitting still at first , than tried driving slow forward and still wouldn't turn. Not sure if diff lock was on or not, had to boost machine to start as batteries were really weak, only thing lit up on dash was the low voltage , after few minutes that went away but machine wouldn't restart, so batteries are pooched.

[kiko]

Boom and steer from one pump though a priority valve.  Sometimes you have to shake the steering wheel or work the blade to free up the pump to make it start. Crossed hoses can make the steering act like that.