I know this is an old thread, but maybe my answer will help someone.
My left signal stayed on after accidentally bumping the stalk. It turns out that there are two plastic pins inside the switch that actuate the mechanism. One had sheared off. I got a small finishing nail and cut it a little longer that the length of the pin on the other side. I heated it red hot and pushed it into the plastic piece where the original pin was. It has been working for over a year now with no problems.

 

that will work..... i just bought a new switch