Is one of the most annoing TI dear friend!!...but apparently you can work out how to fit a ltc1799 for pitch control(this site sell ltc you can easly build and adjust for it)..
i suggest you to replace the "keys" with something more practical...like"proper keys"...
..the best and inspiring result is from the legendary Oceanus..
Circuit Bent Speak & MusicHave fun and be patience with that
Sv