The day began with fetching the morning paper as usual. Less than usual I did not have to unlock the door today because I was unable to do so yesterday evening.
So this morning I tried oil. The weather here in Denmark is a drought currently but in winter I did see dew on the inside of the lock and thought it may be rust.
Oil and time, even more oil and more time did not help. So I tried rust remover. To no avail. Gave in and found a locksmith. Thankfully this trade shares a feature with ER and midwives: A lot of their work is unplanned calls to people who need their help NOW.
The half hour or so was fine, I was not in labour and did not desperately need to leave the house together with my grown daughter. Told him (a rather handsome, youngish man!) what the problem was and what I did.
He then knew exactly what was wrong: The door had a fault from the factory that had allowed too little extra room for the protruding bit of metal to fit into the frame of the door. Apparently all doors sink a little over time. My door had sunk too low by a fraction to give enough room.
Hence the drill: He simply drilled away a bit of the metal. And now it works again!
And the stock bit? I just stocked a couple of items for sale onto my site.