Repair due to falling security thumbturn for TOSTEM QDJ-695

"The thumbturn comes off and I can't lock it from the room"

It looks like a terrace house type apartment. TOSTEM has a security thumb that can be removed by thumb, but what kind of thumb is it?

SHERLOCK-2 was attached. The thumbturn was the type I saw for the first time. It is an idle mode switching type with a slide switch. When I checked it, it was like a security thumbturn for TOSTEM (LIXIL). Is it an OEM product from MIWA?

The knob part comes off easily. Apparently, the screw part of the female screw part of the resin knob part is completely crushed. The cause is unknown. Was it due to aging and lack of durability?

It have to be disassembled it anyway. As disassembly proceeds, the sheer number of parts becomes apparent.

There were several stainless steel balls of about 2 mm and several springs. I proceeded with the work carefully so that these parts would not pop out, but the spring and stainless steel ball popped out from an unexpected place.

(This is a product of a design error. The productivity is low, and the assembly is bad. Furthermore, in order to reduce costs, the material has been changed to resin to reduce durability. The design engineer is too picky. It is a miserable part that is easy to fall into.)

In the end, the stainless steel ball was so troublesome that I had to reassemble it three times.