Please help. If you have the electrical manual I am trying to locate controls on the power amplifier for the center channel.

While washing my car I noticed the panel covering the amp in the passenger footwell out of place and must have been that way since servicing the center channel speaker. I had complained about a buzzing in the center on the demo disks Linda Rhondstat track. The dealer replaced the speaker but now I can't hear any difference in -6 to +6 on the center channel on DTS or the demo DVD. I can only assume they tweaked down the gain for that channel on the amp. I am going to dig out the speaker and see if it is even connected then have a look at the amp but I don't want to go in without a manual.

Any help or thoughts appreciated.