Hartke HA2500 problem

So I got this amp head about a year ago, all is well... but recently I turned on the EQ section and it just went crazy loud and this high pitched noise started comming out of the box. So I looked it up a bit and it seems like it is a faulty EQ section. Now I am looking for suggestions how to fix this?

I know I could just get an EQ pedal but that's just too much gear to carry around, already got an overdrive pedal that annoys me and the super heavy rig doesn't help much at all. Anyone with the same problem or anyone with the knowledge to help me diagnose? Also warranty is not an option.