If you are talking about the ridges on the bearing blocks at each end, here is how they go. If it is a new brush or less than a year old, the side with multiple ridges will face up as you put the brush roller into the machine. If the roller is no longer pulling against the carpet or it is more than a year old, turn both bearing blocks to the side with only one notch showing. That will lower your brush closer to the floor and let it pull against the carpet. If you have it in the lower position and it does not pull, you may need to consider replacing the brush. Hope this helps.
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If you are talking about the ridges on the bearing blocks at each end, here is how they go. If it is a new brush or less than a year old, the side with multiple ridges will face up as you put the brush roller into the machine. If the roller is no longer pulling against the carpet or it is more than a year old, turn both bearing blocks to the side with only one notch showing. That will lower your brush closer to the floor and let it pull against the carpet. If you have it in the lower position and it does not pull, you may need to consider replacing the brush. Hope this helps.