hello all I am new to this site and would very much like some advice on modding a Nerf Vulcan i am in college and a member of my schools Humans Vs Zombies club which use Nerf guns. i have acquired 3 Vulcan EBF 25's however only one of them works like i would like the other two were not stored in an adequate manner and the device used to index the belt into the chamber and the spring are damaged and will not work. are there any ways i can replace them and make them better (I don't want anything to crazy since they will have to be approved before use in the big statewide competition at UMBC) any help at all in the manner of replacing what and where to get these kinds of parts and how to potentially do a mod since i have never done any of these things before would be greatly appreciated. also my apologies if I posted this in the wrong place i'm still trying to figure this forum out, 

Cheers,

Nik S