Famicom light gun problem — trigger not working

[northbydefault]

hoping someone can be brave and open up their beam gun to compare against mine. I was cleaning up today and discovered the trigger and hammer were jammed; I couldn't fire, couldn't pull back the hammer. Didn't want to force anything so I opted to open it up and see what the matter was. Nothing looked broken, didn't look like anything came off... but I cannot figure out how the retention spring goes back on! If I pull the trigger now, it won't turn the hammer (thus "firing" the gun). I can cock the hammer and fire it that way, but the spring will sometimes slip off and I have to disassemble all over again.

Please someone help me out. I don't want to buy another gun just to compare the two

[P]

I wish I had one of these to learn how it works.

Are you sure you got all plastic parts? Try pulling the trigger when the the gun is apart and see if it looks right.
I guess I'm not much help shooting in the dark.