Thank you for your reply, Ron.
Do you think you could illustate on the schematic where to put the resistor and send it back to me. I've tried it on the 'output' but could not see any difference with a larger input signal.
The output transistor is missing because I don't have that part.
When the output current is too high (>0.7V across R19) Q7 comes on and removes the base current from the output Darlington.
You can graph the voltage across R19 and current in Q7-C. and the output current.
You could remove D2. (short)