After 15 years of use, the handle popped off my shower and the attaching screw (not pictured) will no longer thread in the central plastic part you see below.
The assembly does not leak, so can I replace just the plastic threaded part without pulling the whole cartridge?
Do I need a special tubular wrench type tool? The flat edge in the picture below (about 10 o'clock) makes me think that I'm seeing a special nut that can be taken off.
Also, does the house water need to be shut off for this particular procedure?
There are no brand names anywhere. The Delta & Moen videos on youtube aren't giving me any clues either.