I have a Grohe thermostatic shower valve that runs very hot. I realize I probably just need to replace the cartridge, but I'm a much better electrician than plumber! I'm pretty sure the model name is Seabury. I found the following numbers on it: A112 18.M 0504-51
What are the next steps? I think the black plastic thing needs to come off to get to the cartridge, but I don't want to break anything trying to get it off.
Any help is greatly appreciated.