Clothes washer becomes a "drum machine"

It’s vibrating at its resonant frequency due to asymmetrical loading. Since the load is relatively small it can readjust itself when the chatter becomes really loud. If it was a large load that was off-balance, the chatter would be a consistent beat (sixteenth notes?) that would become increasingly loud. Additionally, the load is too small and heavy to evenly distribute itself, ensuring that it will make the machine go off-balance soon after it corrects itself. This is why it sounds like several sixteenth notes followed by a rest of varying length followed by more sixteenth notes.

Some language NSFW.  Via Synthgear.