repair the epicenter audiocontrol Concert Series

hello friends, I am looking to repair a the epicenter at the beginning it started to send a very high frequency or a strong and annoying bass now it does not regulate try to try another control and I had no luck I already checked potentiometers and operational amplifiers and I have not been able to make it work, thanks for your support.
 

Attachments

  • 20220930_142736.jpg
    20220930_142736.jpg
    356.8 KB · Views: 120