No full auto?

[two_zero]

Hello, I have an TM M4 with X1 metal body and systema gearbox. The full auto wont function, that is, the trigger wont even pull to firing position.

Someone advised me that it might just be a case of dissemble it and put it together again. I did this but it failed. After the gun is dissembled and put together again, I can pull the trigger all the way, until I plug in a battery.. Any ideas??

*I can also get it to shoot fullauto when the the grip is not installed.