Hello fellow brickster brethren....

I have a question regarding timing belt issues in my car.

I have a 1980 245. And tonight something happened to the timing belt. I was driving through a parking lot, and I pulled out and all of a sudden the car quit. I tried to restart it but noticed the engine sounded different. It was cranking over faster than normal... So I immediately suspected a problem with the timing belt. After pulling of the upper part of the cover I had my father crank the key, the belt is not moving, but the engine is definitely turning over. The belt looked half-decent from what I could see, So I'm guessing that:

Either the teeth just shredded off of my belt due to belt age? (is this a common problem)

Or Maybe a woodruff key broke or misplaced itself (is this even possible??)

or finally something catastrophic happened in the head causing it to seize up, therefore causing the belt to shred.

I highly doubt option 3 because the car has been running excellent, and the motor sounds great. It barely even had a bit of valve tap.

Any input would be greatly appreciated guys... Thanks in advance.