Hello Jeroen
Here I repeat for you the NEW (correct) modification once again:
The SIMPLEST way to modifiy the output-section of an original K5:
Do NOT replace the original resistors!
But:
Solder eight 22kOhm-Resistors at THE UNDERSIDE of the print PARALLEL to the following original (39kOhm) resistors:
R33, R34, R35, R36, R37, R38, R39, R40.
That`s all.
Best regards
Christian Böckle