Oh the bit attached to the trigger switch, I thought it was the actual mag terminal.
Think I found the problem - incompetent tech, Had this from early days and paid a tech (since vanished) to fit metal gears and fix low fps.
Just looked into the box through the spring retainer - no metal gears. Looks like they stripped some of the threads on the box and have fitted oversized self tappers plus one was too long so they just bent the tip out of the way.
The fitting wasnât installed correctly and had rubbed on a spring and broken
Nothing like having your work done by an expertâŚ
âŚand thatâs nothing like work done done by an expert. 
I hate it when techs donât let people know they fucked up! It happens, offer a discount or extra work/parts and let them know at least!
I have a spare J11 box that I modified to fit SHS gears, then never used as my J12 box never died if you want it.
Worth noting the J12 is a stronger box, has a bit more meat around the gears. Same in shape but the J12 has a thicker area around the bevel gear which is very very good.
Unfortunately looks like this is the only one available
https://x-forcetactical.com.au/product/jm-ak47-gearbox-j11-j12-nylon/
Ihobby seen to have the J12, with the extra material around the b bevel and the non spring mag terminals
Thanks for the tip⌠order placed