Last week my friend's ICS MP5 decided it wasn't going to shoot. I volunteered to take a look. When you hook a battery up and pull the trigger, it makes the regular sound, which lead me to believe it is either the tappet plate or the nozzle. Tonight, I figured out it was neither. After seperating the upper and lower recievers, I found out that the gearbox functions propery. Which means it is a feeding problem. No obstructions of any sort in that feeding 'tube' on the upper reciever. I haven't taken the whole upper reciever apart yet, and I am hesitant to. Any suggestions? Oh, and it isn't the magazine either, because we have tried 3 different magazines, all of which work on my other friend's MP5.