Hi

> I raise the decay and release to 6. Now the sound is clean and
> traveling enough but Portamento is not yet clear if it working on
> VCO4 when switching octaves. I can give a 75% that it remains ON at
> first stage from 16 to 8 and then dies somewhere between 8 and 4.

Sustain for VCA must be to maximum (see the "10" in the graphic
http://fa.utfs.org/diy/korg_monopoly/mp_20_adjustment_1.gif)

Florian