Shower – Uninstal this shower tub valve

A very helpful support contact at Moen managed to put me in touch with someone at Amati Canada, who suggests that it is an "American Sole" unit. I can't find any information that suggests that's a manufacturer, or a line of products or anything -- so I can't corroborate, but at least I may be on the path to finding out who makes it.

Incidentally, in the meantime, I managed to find a workaround for repairing the part that was broken (I found a small plastic bit that sits firmly in the recess and can be screwed on, acting as a sort of bridge between the screw and the cap, so that when you turn the cap, it turns the handle again). It's not a perfect fix, but it's more than adequate for my needs. If I can get the part replaced, I may still, but it's nice to have options.

Glad you found your answer.

I've also had slow leaks (drips) like you experienced due to (1) solder spatter inside the valve that prevented a good seal on the rubber, and (2) plumber soldering the pipe with the cartridge in place which hardened the rubber so it didn't seal well.