Unlocking SHOWA sliding door lock (KH-72) for Sankyo Aluminum

"I have the key, but the door doesn't open."

The key didn't seem to stick.The key is 4 pin. It seems to be KH-72 for SANKYO-TATEYAMA-ALUMI, but it is out of print.The replacement seems to be KH-132.

Normal spray cleaning fixed it, but when I checked after unlocking it, the usual thumbturn was not there.It was a concave thumbturn rather than a convex one.With this, it would be difficult to bypass the thumbturn, so direct picking or another method of bypassing the gap would be difficult.

This time it was usually improved by cylinder cleaning.The lock is still usable, so there is no need to replace it.