New member here so apologies if I’m asking a question that has already been covered.
My wife and I have the opportunity to buy a used Wersi DX500 organ for her to use as a home practice instrument (she is a church organist). The problem is that when we went to see the instrument, it appears that the upper manual is tuned a minor third above the lower manual. (An upper manual “C” matches a lower manual “Eb”.) We could not figure out how to realign the keyboard pitches, and the instrument is unusable in this state. Does anyone here have any idea how to resolve this situation?