Ribbon A (pitch bend) is assigned to pitch bend, but the SP76 or SP88 itself does not respond to pitch bend messages. It does send the controller message out the MIDI port to an external synth, but not to itself.

The mod wheel (Ribbon controller B) lower half controls pan (again the Kurzweil does not respond to pan messages but the messages are sent via MIDI). The mod wheel upper half sends typical mod wheel messages, which some programs on the SP76 and SP88 respond to:

The electric piano and organ sounds this controls the Rotary speaker (Leslie simulator) and speed.

The string sounds this controls the brightness of the strings.

In the Piano&Strings and Elec.Piano&Strings this controls the volume of the strings.