i have just received an hohner string performer
all preset works except the lower piano and the upper violin
i see in the service manual that there is an amp op lm741 for the piano and the violin
but i don't think it was the lm741 because is the lm741 was defect there was no sound upper and lower
for the piano i can hear a very very low sound of piano in the lower section, the same thing for the violin preset but in the upper section of the keyboard
any idea of the problem ? capacitor, diode, resistor
service manual here : https://www.manualslib.com/manual/989770/Hohner-String-Performer.html
see page 15 and 14
thanks a lot