Good add. One more thing: try loosening the blade base ring a hair and reseating the gasket; an overtightened stack can let the blade rub the jar floor and sound like motor grind. With the unit unplugged set the jar on the base and gently rock it; any clicky play between the jar drive and motor coupler means the coupler’s stripping and you should claim warranty so yeah also & too little liquid can cause cavitation that sounds awful - if it quiets when you add liquid, it’s not a bearing issue.
Fresh lemon juice works if you do not want vinegar in the house smell. Squeeze enough to make a few tablespoons and top up with water to cover the scale, bring to a boil and let it sit fifteen to twenty minutes. The scale will soften and wipe off easily and... no scrubbing needed most times. Rinse well and do one plain boil and dump.
How often depends on how crusty your tap water is. For heavy scale do it every week until it calms down, otherwise every month keeps things tasting clean.
