hi casper,congratulation for the website,very helpful!
i'm bending my first toy piano,working on the pitch control.
the original resistor was 51k,so could it be right to connect the hot point to a 100k pot and use two resistors about 12k on + and - connections as peak buffers?
at the moment i tried with what i got,a 500k pot and 6k resistors as buffers and i could notice how out of balance the "system" is (after finding the pot neutral position and starting each time from it,i had a long course to the deep and slow sound,about a turn and a half clockwise,and a really short course rising the pitch,after a quarter of anticlockwise turn the peak was at its top and the circuit was freezing.
i know i tried something wrong,but so i was able to see the effects :) and i hope this note can be helpful to other people.
again,all the best and hope my second guess could be closer to the right one.