A long time ago I bought the AGM-MP007 (MP40) model airsoft gun and I was changing the casing when a part for the fire selector fell out and I was unable to find it again. It has since been stuck in single shot mode and I have no clue as to where I can find a replacement without buying a whole new gear box. I know almost nothing about airsoft repair so I don't know where to look online to find this part. Even if there was a way to force the gun into fully automatic that would be useful.
I've attached a picture of the part that fell out and circled it in blue
Thanks
https://bbguns4less.co.uk/products/agm-mp40-replica-aeg-airsoft-rifle-in-full-metal-in-blue.html