Donald Gillies wrote:

Alternately, take you derailleur to any machine stop and have them
weld a piece of aluminum onto the back of it to recreate the
derailleur stop. Then spent about half an hour with a file and
sandpaper to clean it up.

Good luck,

- Don Gillies

Donald, I'm really curious, were you actually able to spot that damage,
or was it an educated guess?

Also do you know if the extent of heat treatment to that particular
derailleur was so low that welding would not render it useless? I guess
it really doesn't matter, as it's useless now

Regards, John