Grohe - Can't see how to remove handle

Hello,

I have a Grohe 29.238 (discontinued) wall volume control mount. I've taken the thermostatic valve apart a couple of time. But, I can't figure out how to take the handle off the volume control above it. It looks like it should slip off. There is no bolt connecting it on the outside. But, I didn't want to pry it too much in case I'm missing something. Can anyone help me with how to remove the handle so I can get to the cartridge? Attached a pic so you can see what part I mean. Thank you. MRVF

I DOES "slip off" but it takes a lot of force to do it. If you wrap it good and then grip it with Channellock pliers it will pull off.

Thanks - will give that a try.

That did it - thanks!