"Modified" leaves room for ambiguity. I sent in a CW380 about a year ago I think. I had bought it NIB and immediately had issues. The repair report said they "upgraded" the extractor. I believe that means they put in a new extractor made to specs which had changed after mine was manufactured. Anyway it worked.
I never get helpful answers by calling so now I email if I have a problem. On a couple of occasions THEY called ME, and the caller was someone knowledgeable.
I don't change springs unless I notice they need new ones. That does work out to about every 2 years for the recoil springs shooting a couple times a month. I have no idea why you'd need to change springs if you didn't wear them out.
Rest in peace Muggsy
"Individual Muslims may show splendid qualities, but the influence of the religion paralyses the social development of those who follow it. No stronger retrograde force exists in the world." Winston Churchill 1899