Right channel louder, BAT VK-P10SE SuperPak with Ortofon 2M Bronze(MM)


I just received the used unit today :). I used the following setting:
I have used "user" (4 and 8 for S101) and "user" (4 and 8 for S201). S102 is set to "Direct" and S202 is set to "Direct". S2 is set to "Low".Now I notice that right channel is louder than left channel. I tried both Phase setting. What could be the problem?

Any help to diagnose the problem is much appreciated. 

Playing a different source does not exhibit this issue.

Thanks
geek101
I had one of these.  Try swapping the tubes left to right, then front to back. 
My VK-P5 has a trim pot on each channel. I think the P10 has them as well.  They could have gotten set differently.  
@dgarretson There are two rows of tubes and two in between the rows (somewhat). What exactly should I swap. I had to set S2 "high" for volume to be reasonable. Still the same problem.