This is the hot water faucet cartridge for my bath tub. It's had a slow leak, so I wanted to check the washers. I'm at this point now and don't know how to get the cartridge out. When I grab the top nut, the whole thing spins, and when I secure the bottom ring with a vice-grip, I'm not confident enough about direction to really apply the force it wants. The situation is made more complex by the fact that the underside is not accessible. My thanks for any ideas.