You could sew two different ribbons together and set a grommet in the seam. That's basically how the original 4-color ribbon is. Even with the original ribbon you had to wind the ribbon to the middle and undo the ribbon from the vibrator and swap the side the middle grommet is on to change the color.

This was an easy service with the ribbon drive belt being the only issue. I used a 2 1/2 in O ring (link). The original V-belts are ok, so I am living with a little bit of hop in the motor belt.