I am also a great believer in Spyders, some say they are crappy but thats lack of commen sense in knowing what kind of care it needs.
I still have my Spyder Xtra and even though its 3 years old, it still runs fine as long as the Co2 tank has an anti-siphon
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Gold Cup gun oil is highly recommended, and polishing the internals is a really good way to up the marker. Don't ever do changes to the reciever though, as this will end in a big f*ck up.
There are numerous upgrades available from the U.S. also, get on the Kingman message board for further help on upgrades.
Also, go for a decent pre-set 3000psi air system as recommended, cleaner running and the seals will last longer.
Just focus on the specific areas, one at a time.