What does it mean when the motor pulses and I can't use the vacuum?

If your machine detects a blockage, the motor will pulse and you won't be able to use your machine until the blockage has been cleared. If you try to use your machine when the motor is pulsing, it will automatically cut out. You should check the main body, wand, and cleaner head for blockages and ensure all parts are refitted securely before use. (Page 8)