Doepfer

Hi! i wonder if you could kindly help me with this:
i need to make the tune mod to one of my two A-110VCOs, so i can tune them on intervals. as i don't have any electronic experience, a friend offered to do it for me, but since he knows nothing about synths he asked me for accurate instructions of exactly what to do. i searched for all possible info, and, while it's clear that the R5 resistor has to be replaced, there are many different suggestions about the value of the replacement resistor. Perhaps this may have to do with the different versions of A-110, so i should note that, mine are both the early version with only +/-1semitone range. I would very much appreciate if you could give me the right instructions of what value of resistor to install.
Thank you very much.