Repair Yamaha BX 1

Does anyone have information about repairing two Yamaha BX 1 Class A amps, I sent them to a electronics shop in the Detroit area and they said one couldn't be repaired (bridge rec.) because they didn't make the part any more. I really have enjoyed the amps and would like to get them back in working order. Wonder if it is worth the expense. Back in the day I would compare them to the Mark Levinson 331-3332's.