Vacuum belts

Take the old part out and read the number moulded or printed on it, then match that number against the listing rather than matching on brand. Makers run several ranges that look alike from the outside and take entirely different parts, so a brand match is not a model match. Where the old part has no number, the plate on the machine body carries the model number a listing is keyed to.

Roughly annually on a flat rubber belt in regular use, whether or not it looks worn. A stretched belt slips under load long before it breaks, so the lost cleaning arrives quietly. The interval is a starting point rather than a rule, because what actually drives it is how much passes through the machine. A home with shedding pets works through consumables roughly twice as fast as one without, and the guidance in your own manual should win over any general figure.

Sometimes, and the useful test is whether the listing states a specification. A part that names its dimensions, its media grade where relevant, and the specific models it fits is worth considering at any price. One that lists dozens of compatible models with no specification at all is asking you to trust a claim it has not made concrete.

Because most vacuum parts fail gradually rather than outright, so the performance loss arrives quietly and gets attributed to the machine as a whole. That is the mechanism by which working vacuums end up replaced: nothing broke, several cheap things wore, and the sum of them felt like a machine reaching the end of its life.

It depends whether the problem is contamination or wear, and the two produce similar symptoms. Cleaning fixes contamination completely and does nothing at all for wear, so it is worth establishing which one you have before ordering. The diagnostics on this site work through that distinction for each part.