Hello,
My sister, who is a widow and has no access to the internet, asked me to post this:
She lives in an older house which has one toilet, a wall-hung one. In the last week it has started to make a loud rumbling noise after being flushed. This isn't a groaning or clanking noise, but a definite rumble. Everything else works fine with the toilet. She has lived in the house for more than 30 years and this has never happened before. Any ideas? I'm thinking maybe a clogged vent? The ballcock has been replaced.
Dot