Stereo image moves right to left .

As I lower the volume on my integrated amp from listening levels to "background" level, the sound location moves right to left. That is, if Frank is singing "My Way" in the center of the sound stage at listening levels, he moves toward (not completely to) the left speaker as I lower the volume. This happens in standard operation with the integrated amp, and I recently discovered that it continues to happen when I use the pre-amp section as a pre-amp "out" for a new power amp. This of course would suggest that it is a pre-amp problem, but I am pretty much a "dummy" when it comes to higher level electronics. Is this normal? Is it a pre-amp problem? Repairable? Any thoughts would be appreciated. Thanks.
I am guessing your volume control potentiometers (left and right channels) are not linear at the lower end of their range. Is your integrated still under warranty? Even if not, give manufacturer a call - couldn't hurt.
I agree with capt.imho
Thanks Capt. and Wino. I've "e"ed the maker, but no reply in 24 hrs. I guess I'll be a kittle more patient.
The earlier replys are right on. Did this problem just start or did you just recently notice it? If it's a new problem it probably not a manufacturer's defect but rather a dirty potentiometer. If that's so you can try two things. First turn the stereo off. Now rotate the volume control fast and frequently over its full range. This might clean the point contacts. Next level is open the component and look at the potentiometer on the inside. If it has any air gaps use one of those compressed air can cleaners to blow out the dirt or dust. If the problem has always been there then the factory is your only solution.