How would i go about changing the spring in an A&K SVD?

I've ordered one for Christmas and the limit at my airsoft club is 370 ish for snipers which is bad news seeing at the svd is 470. I am fairly new to airsoft this is my second gun where would i get the spring and how would i put it in the gun?How would i go about changing the spring in an A%26amp;K SVD?
You'll have to disassemble the gearbox.

http://airsoft-barracks.com/forums/index



Once you get to removing the spring, just swap it out. As for the spring:

http://www.airsoftgi.com/product_info.ph



You should also consider investing in a decent tightbore and hopup.