DIAGNOSIS You're right to be careful. Mineral scale and mold are the two big enemies, and they need different approaches. Scale clogs things up, while mold makes ice taste funky.
FIX For a routine descaling and clean: 1) Power off and unplug. Dump any ice and water. 2) Make a cleaning solution of 2 cups warm water and 2 cups white vinegar. Pour it into the empty reservoir. 3) Plug in, turn on, and press the 'Clean' button if you have one. If not, just let it run a full ice-making cycle with the vinegar solution. 4) When it's done, dump the ice/vinegar cubes. 5) Run at least two clear water cycles (just fresh water) to rinse everything out before making ice you'll consume.
IF THAT DIDN'T WORK If you still see spots or film, especially in the ice basket or evaporator area, you need a manual wipe-down. After the rinse cycles and with the unit off and unplugged, use a soft cloth dampened with a mild soapy water solution to wipe the interior plastic surfaces and the ice basket. Dry thoroughly.
HEADS UP Never use abrasive scrubbers, bleach, or harsh chemicals. They can damage the plastic and leave residues that get into your ice. Stick to vinegar, lemon juice, or a dedicated appliance cleaner.