Originally Posted by
miamijim
The RD spring is whipped.
Keith, with NO chain installed does the cage 'snap back' when its rotated? It should take a fair amount of effort to rotate the cage by hand and it should easily, if not somewhat forcefully, spring back so that the cage stop is firmly against the derailleur body.
Another reason to Store a bike in the small/small combo. Don't use it there but STORE it there.