It is possible that you have food stuck in your blades. Make sure you turn off your blender and unplug it. Then use a spoon or a spatula to carefully remove to the food and continue to blend. However, if this does not work, check to make sure that you are using the right speed or setting for what you are trying to blend. If this does not work, then you probably have dull blender blends that need to be replaced. If you need more help as to fixing your blender you can go to its troubleshooting page [[Oster 6812 Troubleshooting|here]].