I just went thru this ordeal a few months ago myself. I ended up finding springs at NAPA. Not the "correct" springs but if you take one of your springs to them they can match them up pretty good. I recommend springs that are stiff (hard to compress). The reason for the springs is to create resistance to the round colar when you insert and turn the turn signal assembly back on the steering column. it was quite a PITA job!

Once the turn signal assembly "locks" into place you then tighten those three screws AND YOUR DONE.