Todd, I had a similar problem with my EX21. It was easy to solve the problem, once I figured out what the issue was. What I did, was I removed the white tension lever, then I took a good flat file and I filed the bottom of the lever flat. It seems that after awhile these levers round a bit on the bottom, that makes it so that the tension can cause the lever to flip when under tension. Filing the bottom flattens the base of the lever, and it stops it from flipping on its own. Don't file any more then what is necessary, otherwise you could have other issues with tension. I've done this twice to my saw, and I may get away with doing it once more. But, I now have the material needed to make a new one, so I don't know if I'll even try filing it flat again. You fellas in Newfie land are a pretty resourceful group, I sure you could make one if you get the right material. I got the material to make new ones at a fab shop, you might try to find a small piece there. You don't need a very large piece, it doesn't need to be much larger than your thumb. All you need are a few tools to do the shaping, I used my dremel tools and shapers along with some flat files.
Len