A pic of the spring, and the gun assembly of where you think it might go, will help, as I do not have a parts diagram for the 33 or 33A, and found that Numrich doesn't either. I will continue to look through the books I have, but I don't have a lot on Noble, and it has been a long while since I worked on any Noble guns.
By what I can find, the 235 is essentially the same rifle internally.