See my answer below. You don't need to disassemble -- just use rubber o-rings.

You do not need to take these apart to solve this problem!! If the nylon slides haven't disintegrated completely and fallen out on their own, pick out what's left with tweezers or a hemostat. Then get a pair of rubber o-rings (I can't remember the size I used-- about 3/8" to 1/2"?) and stretch...