Need help from someone that understands electronic boards for Sony Receivers.

This is my third post and I am sorry for that but I have not received much help. I am having a garbled/distorted sound come out of the center channel (still amped because it plays loud). It sounds like a bad AM channel that doesn't have a good signal. Could it be the amp (I wouldn't think so since the center still plays loud) or is it a bad transistor?

Thanks