KSC G23f Repair

[Enceladeus]

I'm fixing this for a team mate, but I'm not sure whats broken and I dont want to go into the hammer trying to find it as these are a pain to get back together

Rubbish picture but it'll help explain the problem. When the trigger is pulled, only this lever moves in the hammer unit. The trigger pull should cause the hammer to spring into the firing position but everything remains stationary apart from the lever. Could this be one of the sear springs damaged?
Secondly, I think the fire selector is a bit loose. Would sorting this be a case of removing the nozzel and tightening it up?
Thanks