If the glass pot has become crusty with burnt coffee, pour some table salt into the pot & then pour in a tray of ice.. Swish the ice around the pot. As the ice glides over the salt, it will scrub off all the coffee that has burnt to the sides of the pot. This isn’t always a quick fix & might need to be repeated. I use vinegar as a preventative to almost everything; so, several times a year, I run a cycle of vinegar through my coffee system to hopefully prevent any nasty buildup problems later. About once or twice a year, I put 2–3 tbsp of baking soda down my kitchen & bathroom drains followed by vinegar until the baking soda stops to foam. I then follow that by 2 cups hot water about 15 minutes later. This cleans most of the grease & grunge that has built up on the insides of the pipes & keeps things flowing much better.