If you can update your MOTM-650 firmware, please use this version:
www.synthtech.com/motm650/motm650rc4.sfi
This fixes the Unison bugs using the Sustain pedal, having 'hangs' when getting
lots of MIDI messages with running status, and 'hanging' when loading/saving
patches with MIDI activity.
As always, if you see any LCD "HOSED" messages, email me with what the display
says and what mode you are in (Poly, Unison, etc).
Paul S.