We have some broken cables too but on a similar note we have a Tetrix motors with a broken gear box and encoder. I've been puzzling about how to get the encoder off without damaging it. I called US Digital tech support and they directed me to this video on how to properly remove the encoder assembly with out damaging the parts.
https://www.youtube.com/watch?featur...&v=6Hx7TvpAJXA