My neighbour's daughter purchased a Karcher wet/dry vacuum cleaner about a year ago. Unfortunately she managed to damage the cartridge filter, both shortening it and splitting it. As a result when she used it the dirt and debris was sucked through the filter and into the motor. After a short while not surprisingly it started to make some strange noises. Her mother mentioned that her daughter was looking for a new vacuum cleaner because the current one was making some strange noises. I said i would have a look at it to see if it could be repaired.
I removed the top from the base unit and then unscrewed the cover from the motor unit.
It was obvious what had happened. The dirt, fluff, hair etc had been sucked through and past the damaged filter and then tried to pass through the motor impeller. Fortunately most of it got trapped on the vanes of the impeller.
The debris can clearly be seen trapped on the vanes of the impeller. This resulted in a high pitched screaming noise when the motor was running.
The debris was removed using tweezers then another vacuum was used to suck out all remaining dust, fluff and debris.
All the rubber seals and gaskets around the motor were removed and cleaned. A vacuum cleaner was used to suck all dust and dirt from around the motor.
While the motor was removed from the casing the brushes were removed and checked to ensure they did not need replacing. When carrying out repairs to other vacuums where the filter or dust bag has failed i have seen situations where the carbon brushes were damaged due to debris, particularly large bits of grit or dirt getting stuck under the brush causing them to burn and fail.
The brushes were in good condition but that should have been expected as the vacuum was not that old,less than a year and had not been greatly used.