The on/off handle on my older Grohmix valve is very hard to turn. When I had a similar problem with another shower that used a Moen valve, I fixed my problem by replaceing the cartridge. The part came with excellent directions and it was an easy fix. My problem is that I am trying to do the same thing with this Grohe valve, but the cartridge, which is very expensive, does not come with directions, just an exploded drawing. It is difficult to find documentation online. My questions is, with this type of valve, which is a thermostat valve, will I solve my problem by replacing the cartridge, or do I need to look elsewhere? Where can I get information on replaceing such a cartridge?

The drain in my bathtub/shower leaks. The previous owner installed it himself and didn't use plumber's putty or a gasket to seal it. I am using "Plumber's Choice" choice right now to seal the leak. This only a quick fix so I can use the shower? How do I get the drain out? Do I have to buy a new drain kit? The drain in there is relatively new. It is the kind that you step on. I have acces the the piping in the basement. Thank you for your assistance.