Same thing happened to my nna554.
I'm in the process of gluing the spring post back on with araldite building the glue up around the base for strength.
It is beginning to look very sturdy and I will order a new latch hook as one of the hooks broke also due to me knocking it.
I would not pay £70 to have the door replaced as it's a shoddy design and the plastic post the retracting spring clips on to is likely to break again.
Alan Humble, September 2010