Audio amplifier

Hi, I am trying to keep my 1991 3000gt SL as original as possible, so I wouldn’t want to replace the radio +cd player, testing new speakers, I realized the front right speaker doesn’t sound as loud as the left one, (yes, I already tried switching the speakers) it is not the speaker. I figure it might be the OEM amplifier but after looking for any videos to guide me to it’s location, I haven’t find any. Can anyone help?

My '91 TT has the amplifier behind the radio/cd player

Thank you. I removed the radio again, and I could see the amplifier. Before removing the amplifier, I want to check the radio out because it has an equalizer. I am trying to find a place where they work on this equipment. I am located in San Antonio, TX. When I removed the AC display for repairs, I had to send it to Houston, TX. Through eBay. Does anyone know of a place where they replace/refurbish these radios in the United States? Mine also loads and ejects the CD very slowly, so it might be worth checking it out.
Thank you again.