Yeah, it's possible that's the issue.
The bolt carrier or whatever you want to call it, part 44 according to the instruction manual, is what the gas piston bits push on to cycle the gun. The bolt carrier thing also blocks the firing pin from being struck when its out of battery.
So if your gas port was full of lead and preventing the gas piston from seating all the way then that could also stop the bolt carrier from going all the way forward and the hammer would strike the carrier rather than the firing pin.
Could be other things too, some bit of crud stuck in the bolt and locking the firing pin solid or a canted / messed up bolt release but given the current known issue of lead fouling of the gas port and piston, I'd just start with that.