HI was wondering if anyone can help me,

Got a 7 ton hyster , while driving when the steering wheel is turned there are occasions that the tires do not follow suit, we then have to steer in the opposite direction to correct it. This is a big problem as when the machine is operated with load, we find that when we turn, the machine keeps going straight. In saying that it happens 3 times out of 50 turns.

We replaced the steering pump and checked everything but still cant find the problem.

Any ideas guys ?