Issue with G&G GR16 CRW

[poachedeggz]

Got this old gun from someone I know so there are issues to be expected. But when I shoot it, it will be fine and then all of a sudden it stops shooting, however it sounds and feels like the motor is still moving and a loud clunking noise starts and it feels like something somewhere is loose. In the picture I've added I've circled a little gap behind the hop up where I can see something moving when I fire the gun and it doesn't look very consistent with its moving backwards and forwards.

I'm still new to airsoft so have absolutely no idea what could be wrong. I'm hoping it's something that can be fixed and if so can anyone recommend someone who can repair airsoft guns?

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