Try to contact Steve/Terry at (216) 544-6615.Terry repaired a 401S without schematics.It appears as though the driver transistors are not adequately heat-sinked and will pop.You may need to contact member Nexusrlee,as I understand that he bought the remaining transistors used in that amp-driver/output.If so,eome else works on it,be sure to check the drivers/They will measure fone while in idle.bot are actually damaged.