The Left cancel spring may be all that is broken. You may be able to buy just the spring. It has been several years since I have bought just a spring, but the last one I bought, I bought from my employer (Chev Dealership).
Look at the picture. You can see a screw driver in a screw in the upper left area of the picture. Just down a bit and to the right there is a circular metal spring. It is by the light colored open area of the T/S switch. The spring is what the cancel cam pushes against to turn the turn signal off. These springs break.
