Zimmerframe and Collective Bias,
I recall one yaw control problem like this in the long ago past on S-76's (maybe 1980), but it was an oddball, not a typical stuck control/cable/pedal type situation. The tail servo wore a notch in itself after a long time, and the servo just sort of locked itself in the cruise tail pitch position. The pilot (Gulf of Mexico) and I spoke the afternoon of the occurrance. He did a great job of flying home and made a very high speed running landing (about 80 knots as I recall. It might have been possible for him to slow down to the other side of the power required curve and get to 40 knots or so if he had done a near autorotation, but never argue with success! When he bottomed collective on landing, the turn was a mighty one, and he had to chop throttles and stand on one brake to stop the machine. We modified the servo to prevent any recurrence.
Some observations on all this:
1) He really never figured out that it was a yaw problem, because with the yaw/collective mixing as he pressed hard on the pedals, he stopped the collective from going full down. He wasn't sure, but thought he had a stuck collective!
2) When he made his approach, he did what good pilots always do, he sized up what he could do, and made it all come together near the ground. He touched down with no yaw, but at high speed.
3) When he and I spoke, he was not fully convinced that it was a tail servo problem, but they checked the servo and confirmed the guess.
4) The next morning, he told me that his leg really hurt from all the pushing he was doing all the way home, done inadvertantly and instinctively, based on thousands of hours of automatic pedal motions!
I know of no other stuck control problems on the 76 family. Does this one sound like the one you were referring to?
A comment on simulator training - most training sims are not to be believed if you leave the normal flight envelope. Several sims I have flown are quite benign in emergencies that might very well be eye watering. They are excellent procedural guides, but not tools to polish technique or study the effects of large, improbable failures.