Originally Posted by
JoelS
I've had limit screws creep. They do need to be checked periodically.
I've never had the limit screws on any derailleur change spontaneously but I did have a rear derailleur ( a week old Ultegra 9-speed!
) destroyed when the chain grabbed a piece of steel wire thrown up by the front wheel and ran (or tried to anyway) it through the derailleur. Fortunately, only the derailleur was trashed and the dropout was ok.