GOAL thumb-latch decorative lock operation defect repair

"GOAL GF lock, door knob doesn't work properly"

It seems that the latch bolt is malfunctioning for some reason. The entrance door is a set of 1K2L, including the auxiliary lock. The target was the main lock. The door knob from the inside does not fully retract the latch. The same is true for the cylinder side.

I disassembled it and found that it was malfunctioning due to aged deterioration of the tubular lock.

Completed with normal cleaning and lubrication work. When I reported that there was no need to replace it, they were happy to say that it was done cheaply.