Hey, Mike, welcome to the GTA! The stock spring in my CFX lasted less than 2000 shots, then broke. Sometimes you can see the break if you pull the action out of the stock and look in the slot on the bottom of the spring tube. Mine was also under warranty, but my feeling was the same as yours, why replace junk with more junk? So I sent it to Charlie for a tune. I had some other issues with that rifle, that Charlie helped clear up even though they weren't his responsibility. Great shooter until the second spring collapsed. Sheer bad luck, but by then, I was interested in gas rams, so that's what I ended up installing. With your mechanical ability and experience, you'd have no problem doing a home lube/tune. If you have some machining ability, so much the better. Lots of info here on tunes, compressors, anything else you'd need to know. You might also do a search on the Yellow Forum:
http://www.network54.com/Forum/79537/Can't remember all the details, but there's a guy that did a tune on a CFX, and posted what amounted to a tutorial on the forum. I'll see if I can find the link and post it, just in case. BTW, the internals of almost ALL the Gamo rifles are essentially identical, so info on one will carry over to the others. Good luck!
Dave