DIAGNOSIS That gurgling/choking noise is usually caused by a clog or airlock in the internal water line, often from mineral scale buildup or a kinked tube.
FIX Run a full water reservoir of plain white vinegar through a brew cycle (without coffee, obviously). Let it sit in the system for 30 minutes, then run 2-3 full reservoirs of clean water through to rinse. This dissolves the scale that's blocking smooth water flow. Also, check that the water reservoir is seated all the way down and the lid is on tight—an air leak can cause weird noises.
IF THAT DIDN'T WORK Inspect the small silicone tube that runs from the water reservoir to the pump inside the machine. If it's kinked or pinched where it connects, it can create that sound. You might need to open the back panel (unplug it first!) to check the tube's path.
HEADS UP Never use descaling tablets or powders meant for pod machines or Keurigs. Stick to plain white vinegar or a liquid descaling solution approved for drip coffee makers. Harsh chemicals can damage the internal seals.