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
![[WE-Tech] Airsoft M4 Upper Receiver[For WE-Tech M4 GBB Series]](http://www.sixmm.com/cdn/shop/products/WE-Tech_AirsoftM4UpperReceiver_ForWE-TechM4GBBSeries_2.jpg?v=1634123538&width=950)
![[WE-Tech] Airsoft M4 Upper Receiver[For WE-Tech M4 GBB Series]](http://www.sixmm.com/cdn/shop/products/WE-Tech_AirsoftM4UpperReceiver_ForWE-TechM4GBBSeries_1.jpg?v=1634123537&width=950)