Mine just recently started acting up on 1-2 voices. One was well off pitch and only playing through the right channel. The other was pretty decent sounding in most patches but would sometimes drop volume so low it was near silent and would sometimes crackle out of the left channel. I reset global settings, reset calibration settings, and recalibrated many times. It always hung up on L2 & L3 in the calibration sequence with several other spots where it would sit thinking for a couple minutes (41 was a common dwell spot). I updated OS to 1.4.0 and still no improvement. Finally I opened the machine up and reseated the 6 voice cards. I gently removed them from their sockets and reseated them firmly. I then powered it up and tried a recalibration sequence again. It zipped through the sequence with no hanging points and completed it! Now all the voices sound equal in volume, stereo position, and pitch (save for the slight variation that makes the magic). If you are not accustomed to handling and reseating PC board parts you might have a more savvy friend help with the process. Be really gentle and preferably make sure you are grounded when handling the boards.