I have a GE XL. I have a GE XL 1800 spacesaver. I'm attempting at swapping out the magnetron

Question

I have a GE XL 1800 spacesaver. I'm attempting at swapping out the magnetron myself. One day it just stopped heating. Everything else worked fine, but normal sound of microwave was null and void. I called GE; they said they know of the problem, part will be free, but I'll have to pay for labor and service call..... I want to try to tackle this thing myself... Do you have any instructions/downloads that I may use to access this thing and swap it out? Thank you for your help!