1. Check vents are not blocked by and dust or dirt.
  2. Please ensure that you are using the correct line for the model.
  3. Please check that the line is correctly wound round the spool.
  4. Please try the additional spool and line that comes with the product.
  5. Please ensure that you are using the correct line for the trimmer (i.e. diameter of line according to manual specifications: generally, 1.2mm)
  6. If the problem persists please contact the customer service helpline via livechat or email.