I recently had a Peavey Stereo Chorus 400(The Beast) come in for repair, this amp did nothing. Step #1 visual inspection. The thing had this large steel wheels mounted on it it , If a amp has wheels it's being moved CHECK FOR LOOSE SOLDER JOINTS. I check this thing from input to speaker output before it dawned on to me to check the @#$% solder joints. I have been doing this for more years than I care to talk about , so in short always check the basics. The loose solder joints where on those 4700uF caps that give you the -43(not 53) and +43 volts the power the power transistors.
Rock On
Rock On