Korg Mono/Poly

heya guys!

some time ago i opened my mono/poly to tune the 4 oscilators so that when all the tune kobs face zero, it would play everything in tune. well after a really time consuming operation, i managed to do so, but it was only later that i noticed that OSC 4 keytrack is not correct. to avoid a long process of messing around something again, i was hoping that someone here could tell me what exact potentiometer i should adjust to get the keytrack of OSC 4 corrected.

thanks!

.michael