Hello everyone, I picked up a Fender 100SB bass head from a second hand shop who told me it was working perfectly and had been tested. I took it home to use with the intention of using it as a guitar amp (classic Bassman style), and it sounded awful compared to my other smaller bass setup. Hardly any treble on tap, the mids and frequency knobs didn't work at all and with the gain turned up it started cutting out then fading back in. I opened it up and this is what I found on the circuit board, around the gain pot end. Not knowing much about amps, I'm worried as to what it even is, and if it's fixable. Any suggestions?