Have a timegrapher 1000 that usually works fine but I have a Elgin 291 that when I put it on to test all I get is about a half inch of graph on the screen and then the grapher stops and starts over. I put other watches on and it works fine . Don't know what is going on. Can anyone help me understand what is happening.

It just means that your watch is so far out of spec that the timegrapher can't get a reliable reading. When this happens all you can do is fall back to fundamental trouble shooting.