power steering issue

2002 jeep liberty 3.7L six cylinder Engine -power steering pump failure.this is the about the third time I am-- actually this will make it the 4th time in about 1.5 years I am replacing it.the last time by a certified repair facility.I also had the hi-pressure steering hose replace due to leakage.What else could cause this failure.I did notice I have to keep a bit of right steering pressure to keep the car straight,but I did not feel as though it was that pronunce enough to cause problems,besides now I am just stabbing in the dark.I appreciate any help I can get.
Thanks
soccermech