I was able to pry/pull off the handle for my shower, and it mounts onto a T-shaped plastic arm that is the control arm (?). It's a single knob style, with a chrome plate around it.
I'd like to replace the handle. So I took it to HD, but two plumbing guys there both looked at it and said "no" - it's not compatible with what they sell. I don't know the brand, unfortunately.
Any suggestions for online shops, or how else to find compatible handles?
Thanks.