Ok, thanks for the link Mack The Knife.
It is the one in the middle here:
http://www.indianhumepipe.com/index1.html named I.H.P 35 Air Rifle. That's the one that has a forward-pointing arrow with the initials "CB" in a maze, marked on top of the the receiver and below the arrow the inscription "CLASSIC CDM-45". Now I know that it is indeed a Diana 35 copy. It shoots pretty well and if the Law allows I would buy one next time in India (in a few months).
I've seen a few more airguns in Chennai and Trivandrum gun shops. Some looked Chinese copies of rather poor quality. The National CDM-45 was far better made, by comparison, and shot just fine.
I am sure that a Maccari spring with heavy tar and a new breech and piston seals it would rock!
The pellets could do w/some lubricant as they were turning gray from lead corrosion. Nothing to it as a drop of parafin would revive them in a jiffy,
Cheers and kind thanks for the Indian Hume Pipe link,
Nikos