[USER=993]@lux14[/USER]: It wouldn't surprise me if a majority of folks (who are not vacuum fanatics) treat their machines like anything else, very little maintenance if any, or until an issue occurs. I know people who hardly ever change the oil in their car and never think about their transmission or differential fluid. If they don't take care of a high dollar item, I doubt they would bother to flip the vacuum over to check out the brushroll.
I tried a Kirby once, but it was too big and bulky and wouldn't fit under any of my kitchen chairs and was a bit awkward to move around. Also, I didn't have enough carpet in the house to make it worthwhile.