well I don´t know if is to late, but I have all the info you need in my site, (again, is in spanish but you will know what to do)
just go to http://www.tk7606.com/ enter to Stormtrooper/Tutorial MG-15 from the menu
You will find diagrams on ensambling, meassures, pics step by step and upgrades
anything I can help just tell me bro