Popping sound out the right earcup

Hi everyone

I’m looking for help this pair of headphones I got out of a salvage lot. And the repair I thought was just to clean the microphone due to the insane screeching it was making that did fix it and now it’s making like a low popping sound almost like it wants to make the loud screeching again but it won’t does anyone know what else it could be? I also did push the copper wires away from each other.