DIAGNOSIS: Scale and biofilm buildup in the internal water pathways, which the exterior wipe-down doesn't address. This causes slow ice production and off-tasting ice.
FIX: Power off the machine. Fill the reservoir with a 50/50 mix of white vinegar and water. Run a full ice-making cycle, discarding the first two batches of vinegar-ice. Then, run two cycles with fresh water to rinse.
IF THAT DIDN'T WORK: For heavy scale, use a commercial ice machine cleaner (like Foster's or Dezcal) following its product-specific instructions. These are stronger than vinegar for hard water deposits.
HEADS UP: Never use bleach or abrasive scrubbers on the interior. They can damage the plastic and leave a residue that gets pumped into your ice.