100w Major build. Played all weekend, loved the sound, better than ever after changing mic positions. Tonight after work it still sounded good, then, almost without realising, playing a B note on the sixth string with the neck pickup had this horrible, bassy, muddy, boomy sound. Couldn't believe my ears. I checked the circuit, poked around with a wooden stick, found no loose connections in the preamp and pots. Turned the Mains back ON and when I turned Standby ON there was a loud spark but the amp was still working and there was no smoke. Turned it off and when I checked underneath the board I saw the wire that goes from the rectifier diodes to the first electrolytic hanging by a thread. Replaced the wire thinking it was going to fix the problem. But it didn't. The muddy bass is still there. Highs were afffected less but overall the sound of the amp is horrible compared to its usual self. What should I try next?