You may be able to grind a groove into the broken pin with a dremel and unscrew it with a screwdriver.
I have a Motion Pro 08-0001 that has been used no fewer than 200 times. I've gone through about 6 pins, but they're fairly cheap and very easy to replace if they break off. They do not break off easily though, and just about every one that broke for me has been when I wasn't paying full attention. AND, they're made in the USA!!