Colt Customer Service referred me to Jack First Gun Parts:
Jack First Gunshop - First in Gun Parts - Rapid City, South Dakota
Numrich, If you can find it in stock:
numrich gun parts - Google Search
World's Largest Supplier of Gun Parts, Gunsmith Tools & Shooting Accessories - Brownells
Python Parts are starting to get rare. I just wanted a mainspring. Jack First was the only place that had one (they make their own in-house). Your part sounds like a bit of a problem. I was told that in the not too distant future, I may need to see a machinist in some instances. Mine may head into semi-retirement.