sometimes the ics can jam, mine did once - separted the upper receiver - checked gearing - worked ok after that read instructions about checking gear position - might work
get somebody to help ya if you are not sure, seperate upper receiver, try a few shots on semi then it should be correct position to refit - check manual about this though - or take to skirmish and get them to look at it if you not sure
My parents are the least understanding people. Things like this happen and they say "You've broken it already?" no I haven't.