Hello

Am 09.03.2012 14:24, schrieb dir_marillion:

> Is the TL072CP under the capacitors (inside the circle)

Yes. There are two, but the one which affects VCO4 is under the second
bentover capacitor (counted from the bottom of the circle).

> Do you suggest to replace the TL072 or I may have a damaged 4006

There is a basic principle of search for faults: never change two things
in the same step.

So the order of steps should be:
* Replace IC10 (TL072)
* Check the portamento of voice 4
* If it does not work: check the fourfolded portamento potentiometer, in
case of doubt shortcut in each layer of the potentiometer the two outer
contacts
* Check the portamento of voice 4
* If it does not work: insert a cable into the portamento socket (this
switches the 4066).
* Check the portamento of voice 4

> Second question. As VC04 is also detuned about 4 notes and I do not
> have the KLM398, which are the switches for the 4rth VCO that I have
> to tune I show two white circle tuners under the fourth VCO (check
> my uploaded picture).

You don't need KLM398, but only KLM354. I described the tuning procedure
in detail at http://fa.utfs.org/diy/korg_monopoly/vco_adjustment.html
I would NOT do the full procedure, but simply try to change the offset
with VR402
See
http://fa.utfs.org/diy/korg_monopoly/mp_16_klm_354_layout_TRIMMERS.jpg
the most left light green marking at the bottom named with "tune offset"

Florian