Vacuum cleaners have belts. Most belts are rubber. Rubber wears out and breaks (or worse yet, they slip, so when a good-intentioned consumer checks it, it's not broken, so "it must be fine". When a stretched belt is put on the floor, the carpet stops or slows the brush, & you say to yourself, "there's no suction!" A belt is a few dollars and a few dollars labor and a couple minutes of your time, so do it at least once per year (twice a year is better). We sell a lot of belts to guys that find vacuums in the garbage - a belt was all they needed!
P.S.: Some of the better vacuums cannot be sold on-line anyway, or the MAP (Minimum Advertised Pricing) allowable by the manufacturer is much higher than what it may sell for in-house. So what's left to peruse on the web is never all that there is, & many retailer & e-retailers are mostly offering medium-to-lower-quality machines.
Thanks to The Henry Co.