Well, it looks like the slide portion is "stuck" at one end of the travel - if you can move it away from that end a little bit (after removal), then there should be 3 pins on the part that you can ohm out with a multi-meter; set the meter to something like 10K ohms, and put the leads across two of the pins; with the slide positioned part way (if you can roughly center it, even better), two of the pins will measure one value, and the other too will measure a lower value. You want the higher value (of course, if it goes out of range, move to the next higher setting on the meter). That will tell you its value in ohms; with the size measurements and that, you can at least find something close. Note that you will probably want to measure the length of the piece that broke off, and check the specs for the length of that piece two (should be on one of the last sheets listing dimensions). Find something close, or longer (and then do some hacking on it to reduce it to the right length - take a dremel or x-acto to it)...