Your vacuum should be serviced every 12 to 18 months.
As dirt, dust and lint build up in your vacuum cleaner; bearings slow down the brush roll causing excessive wear on the vacuum motor. Overheating can drastically shorten the life of a vacuum motor or even require total replacement of the entire vacuum. Over a period of time some brushes become soft, lose effectiveness and need to be replaced. A worn out brush may look fine, but if a worn brush is not replaced, it will simply turn, never touching the carpet. This cuts your cleaning efficiency by as much as 50 percent.
The overall appearance of your carpet depends on a good vacuum cleaner. If your vacuum cleaner has enough air flow and suction to lift the carpet nap to the brushes, the vacuum will brush the nap and help it to stand up properly. The result will be newer looking and easier to clean carpeting. This will help to reduce dirt and allergens in your home.
If your vacuum is performing poorly, the carpet nap will remain matted and packed down from foot traffic. Sand and grit cannot be pulled from flattened carpet fibers. Dark colored traffic trails begin to appear cheap real shoes. As the sand and dirt build up, it acts like sandpaper, slowly wearing and cutting the carpet fibers as you walk across it. A poorly maintained vacuum can greatly reduce the life expectancy of a carpet.
As regular maintenance, you should check the cord for cracks and listen for any unusual noises. If you are using a vacuum that has been repaired with duct tape and wire ties, you should probably bring it in for servicing. Repairing your vacuum is far cheaper than replacing your carpets!