Rig Magician, Have you tried Numrich Arms or Brownells?
I am pretty sure that Wolff would make springs for your gun, but I cannot remember if they have direct sales or not. I have not had to buy springs in a while as the last time I did I bought enough to last a few decades!
If you Google up those three, I feel certain that at least one of those companies would be able to help you out.
I hope this helps.
Willy