Well you can start by ordering the lube kit from rich from mich.
This is the kit:
http://home.comcast.net/~peterdragin/index.html/My_Homepage_Files/Page11.html
It costs $8.00 for the kit.
Here is his homepage if you want to check out his other products:
http://home.comcast.net/~peterdragin/index.html/
The next thing you can do is use Bel-ray waterproof grease on metal to metal surfaces and linkages.
It is petroleum based i believe so keep it on metal to metal only.
You can buy it from most motorcycle stores or dealearships.
This is a description of the Bel-ray.
http://www.belray.com/consumer/product.fsp?pid=13631
The airgun should be like brand new after this.