My power steering pump on my 73 screams when at full lock. It also will do it the odd time before full lock if the car is hardly moving. It seems to me its when the pump is loaded up. Fluid level is correct Lines appear to be tight...I guess suction could be still be leaking but... Car has had less than 3000 miles since restoration 10ish years ago so I can't see that the fluid needs to be changed. What is the likely cause of the pump screaming? Do I need to change the pump?