How can I fix a wall-mounted toilet that keeps running?
We had a similar problem with our Duravit toilet.  We followed the instructions above, and after pulling out both the intake water controller portion, as well as the flush control, he didn't find any calcium build-up: just some rust stains.   As a final check, my husband reached down into the toilet tank and felt something stuck in the bottom stopper valve. He felt what he thought was a broken piece of rubber, and after tugging on it with some force, he pulled the foreign object out in his hand from the access hole in the wall, and found a perfectly intact, but dead scorpion]2  It must have died just that morning when the toilet started running. Luckily he wasn't stung.