Check whether there's a collection bag fixed inside the cleaner, and if so and it's full, fit a fresh one (unless yours is a Dyson). Some vacuum cleaners have a separate filter fitted too - check that this is not blocked.
Wise Owl
July 2010
A "racing" motor on a vacuum cleaner is symptomatic of no load on the motor (no air to shift) - will make a higher pitched sound - let some air in for the motor/fan to work against and the motor will slow down, If your motor is racing then there's a blockage of some sort some where.
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Try fixfault.com to fix vacuum cleaners.