At Japanese tavern "IZAKAYA", ALPHA sliding door lock with key, cylinder breaking and unlocking due to malfunction

"The key no longer sticks deep"

ALPHA sliding door lock "No.4600 large sickle lock" was installed. I was told the key wouldn't stick.

Certainly the key does not stick to the back. I thought that it might be malfunctioning due to aged deterioration, so I performed normal cleaning, but it was not improved.

The number of pins is 4, but if you look into the back of the cylinder, there is something like a wall on the keyway. This is getting in the way.

Different from normal position. You can't see it. After all, only this wall was destroyed. I was able to unlock it with the key.

After that, replace it with a new one and you're done. The true cause remains unknown.