Have you taken it apart to figure out what exatly broke? I've tinkered with them for a few years. I 'might' be able to help you.
And, they are easier to take apart than to put back together...But, it can be done. Start with a BIG white towel and keep a magnet handy.
http://www.schludershots.com/index2....tmpl=component
http://www.gunpartscorp.com/Manufact...nger-36042.htm