Does any one know?

Comanche revolvers were the flagship of Gabilondo's revolver range produced from 1975 -1997. They were copies of large framed Smith & Wesson revolvers. Although of a very high standard, they were unable to compete successfully in the US market.

Since they are copies of the S&W, try to find a reliable S&W gunsmith.

I would just try a local and reputable Gunsmith-- As the Comanche design isn't anything much different than a S&W, you should be ok sending it to someone who is well versed in the revolver "arts"...