As she was settling in, we noticed a loud double BANG as the door opened. Upon examination, the folding arm from the free swing door closing device was snagging on the top of the door.
Stand back everyone, I am a fire safety expert. However as I perched on a chair forcefully 'adjusted' the arm, snap - it came off in my hand

"Yep, that's what it was" I announced "The arm is broken"
I think I got away with it
