Originally Posted by
jimc101
Why was the old one damaged? is the hanger straight?
That's what I think too.
Bent derailleur hangers are common. A damaged derailleur makes me suspect a bent derailleur hanger and, the symptoms that you describe are frequently caused by a bent derailleur hanger. Shops have a tool for realigning hangers. It's only about a 10 minute job so it shouldn't cost too much.