Need assistance with Echo 1 AKM

Privet, comrades.
Recently, I have encountered a problem with one of my back-up replicas (Echo 1 Red Star AKM) that has baffled me to the point of breaking my rock-solid stubbornness and asking for help.

When I discharge about five to ten rounds, it just stops firing completely. I have to shake it for a minute or two for it to work again, but the problem persists after firing another burst. It generates a soft whirring noise as if it's battery is dead, and using a different battery doesn't work. Changing the fuse also did not help.

I stripped the gun down to it's internals at least three or four times, and carefully checked to see if there were any breaks in the wiring or if the gearbox was messed up... No dice. The motor appears fine, too. I've tried just about everything!

I'm pretty experienced with AEG internals, but I've never run into anything like this before. Any advice? I really don't have the money to bring it to the shop at the moment...

Elaborate the whirring noise...my top two guesses were a stripped gear/motor issue, or wiring.
But it looks like youve covered those two

random idea, but could it overheat, or somehow the motor skip out of position (unlikely)

I suppose I might just have to take it in for repairs...

Say goodbye to $50 put of my pocket