Question about Audio Research LS2B MKII

Hi, I have a LS2B MKII upgraded from LS2 few years ago. I realized that there is a gain difference between left and right output. I tried both RCA and balanced output. When I turn the vol. down(maybe few degree). I can hear only the right output. Is it a problem? How to fix it? Please help! Thanks for your attention!
I also have the same preamp, with remote.

I have not experienced a problem such as you describe, in fact my unit has performed without any problems, but you might try replacing the 6922 tube. I'm certainly no expert, but it seems to me that half of that dual circuit tube may be at fault.

Best of luck-
This problem can occur from time to time and the problem in most cases lies with the volume pot. Replace it and should cure the problem.