Turn Signal Handle Won't Return!

[84MB500SEL]

In the past, with semi-extreme temps (below 30 or above 90), the left turn signal in my '84 500SEL would not return back to neutral after coming out of a turn. I figured I would live with it until it got worse. Well, this morning, when it was like 30 degrees out, I was coming out of a left turn when I heard a cracking sound behind my steering wheel. Since hearing this sound, neither the left or right turn signal will return to its neutral position under any conditions! I think something behind the steering wheel broke this morning in the cold, so I was wondering if this was fixable. What exactly is the problem, and has anybody else had this problem? Does anybody have the procedure to fix it? How long/difficult is the procedure, and would I be better off taking it to a mechanic? If I take it to an experienced mechanic, about how many hours would he charge for labor? Any input on this problem would be appreciated!