Oh very dear....

Where to start old son, we shall skip past the part about your actually going into a shop and asking the nice man for a well ard cast monkey metal replica of Mel Gibson's piece in Lethal Weapon

The truth is they aren't designed for any serious usage, I would guess that repeatedly dry firing it while prancing around naked pretending to be Bruce Willis has simply worn the poor thing out.

Seen dozens of them and the best solution is to bin it and buy something made of steel and wood like proper guns.