The smell is likely from mineral deposits and old coffee oils. You need to descale and clean the internal water path.
- Fill the reservoir with a mixture of equal parts white vinegar and cold water up to the 12-cup line.
- Place an empty filter in the basket and put the empty carafe on the warming plate.
- Start a full brew cycle. Let half the vinegar solution run through, then pause the cycle for 30 minutes before resuming to let it soak.
- Once the cycle is complete, discard the vinegar from the carafe.
- Run 2-3 cycles with fresh cold water only to thoroughly rinse the system.
If that didn't work, also wash all removable parts—the carafe, filter basket, and reservoir lid—in warm, soapy water.
Heads up: Perform this descaling process every 3-6 months, or more often if you have hard water.