So about two weeks ago my 9-cup pot started failing. Instead of a nice rich flow, it did nothing until it started to boil, and then produced about 3 of it’s 9 ‘cups’ via a disgusting tasting over boiled sputtering mess.
I changed the filter. I cleaned the interior with a toothbrush. I blamed the beans. I blamed the grind. I was wrong every time. I was in despair. I youtubed.
https://youtu.be/4yGinq5NaCA?feature=shared
TL;DW: use thread tape to correct the fit between the funnel and the top of the water container. Works great!
Try changing the gasket as another poster suggested.
I did. I forgot to mention that. The actual problem was that the funnel no longer sealed tightly with the water container. Using thread tape repaired the seal. Replacing the funnel would also work, but thread tape is very inexpensive.