I'd second just getting a new derailleur. Repairing a $10 der. with a $20 part makes no sense and you run the risk of it not fitting or there being other damage you can't see. Any 8,9,10 derailleur will fit and you can use other brands like microshift too. Shift quality with a new part may improve also.
Here's one for $20 new.
https://ebay.us/m/5gxN0U