I didn't remove the metal parts at the back no, just the innerbarrel/hopup and the recoil spring.
I could honestly try but I wouldn't want to cause any irreperable damage if the fix you suggested doesn't work. Thankfully there is a shop just outside of Cambridge I can take it to, about 25 minutes on the bus. But I just wanna be sure in case I make a 25 minute journey for something that could be fixed at home. What do you think could be the Issue and how would filing down that bit fix it? I apologise if I seem like a noob, I am new to this hobby and not too familiar with all the technical parts yet.