You may need to adjust the height of the bowl tool. With the mixer switched off and unplugged, insert the beater or whisk and lower the mixer head.
Check the clearance between the tool and the bottom of the bowl. Ideally the tool should be almost touching the bottom of the bowl.
If the clearance needs to be adjusted, raise the mixer head and remove the tool. Using a suitable spanner loosen the nut sufficiently to allow adjustment of the shaft. To lower the tool closer to the bottom of the bowl, turn the tool shaft anti-clockwise. To raise the tool away from the bottom of the bowl turn the shaft clockwise. Tighten the nut.
Fit the tool to the mixer and lower the mixer head. Check its position. Repeat the above steps as necessary until the tool is set correctly. Once this is achieved tighten the nut securely. No adjustment of the dough hook is necessary.