I had to take apart as wasn’t working to find the slider had snapped along with plastic on wheel to had split , thankfully I had these from old gearbox and was able to get firing as gears are good,was going to complain but left too long before I tested
![[5KU] M4M16 SI Shift Pins [For M4 GBBPTWDTW][BLK]](http://www.sixmm.com/cdn/shop/products/5KU_M4M16SIShiftPins_ForM4GBBPTWDTW_BLK_1.jpg?v=1620659777&width=950)
![[5KU] M4M16 SI Shift Pins [For M4 GBBPTWDTW][BLK]](http://www.sixmm.com/cdn/shop/products/5KU_M4M16SIShiftPins_ForM4GBBPTWDTW_BLK_2.jpg?v=1620659780&width=950)