what actually works to clean washing machine with vinegar?

Empty drum, hottest cycle, a couple of cups of white vinegar in the drum. Then a second hot cycle with a bit of baking soda to finish off. The bit that makes the real difference isn't the vinegar though: pull the detergent drawer right out and scrub it, and on a front loader peel back the rubber door seal and wipe out the black gunk in the fold. Also clean the drain filter at the bottom front if yours has one, have a towel ready. Leave the door open afterwards to dry.