This iconic little amp came in to the workshop for some TLC. Not much wrong really. A blown internal fuse but bias and every other parameter measured fine. So once checked and the fuse replaced the amp works fine and sounds good. There is a noticeable thump on switch on, which is typical for an amp of this age as capacitors and transistors age. A recap and change of transistor would cure this but for an amplifier of this age, I often simply install a slow start module as a cheaper fix for switch on thump. It really depends on how much the owner likes the amp and wants to invest in its future.