The cutting deck is not correctly adjusted. The rear of the cutting deck should be 0.5 cm higher than the front, measured at the outside ends of the blades. The instruction book for your lawnmower shows you how to make this adjustment.
The grass is too wet or too long. Let the grass dry or cut on a higher setting. Then reduce the cutting height a bit at a time until the grass is cut to the length you want. The rule of thumb is not to cut more than 1/3 of the length of the grass.
The wrong blades are fitted or the blades are worn. Replace the blades with the correct type of blade for the cutting method you are using.
The blades may be incorrectly fitted. Make sure the blades are fitted in the correct direction.
The engine speed is too low. The engine has to be running at full throttle to reach the correct blade speed.
The mower is moving too quickly. Mow more slowly.
The drive belt to the cutting deck may be worn. Replace the drive belt with a new one with the correct part number. You can buy this from your local dealer.
The ventilation holes in the blade spindle may be blocked. Clear any grass clippings from the cutting deck.
If the problem persists, we recommend you contact your local dealer. A list of dealers is available under Service locator above.