Firstly, blade depth is all important, it should just be cutting into the surface of the slipmat. The longer the blade tip the more flexible it becomes and will obviously bend easier.  This is the most common reason for ‘hooks’ at the start of the cut.

Then check the cutting head and the blade holder has minimal (ideally zero) side play or the board will use that loose movement to pull the blade slightly off track and once the blade starts to veer offline it will bend the blade tip so it can continue on its path. Then sometimes, on a large mount, you may find the blade comes back in as the cut progresses, this could be due to your arm/elbow position influencing the attitude of the cutting head as you pull the head towards you.  The cutting head on the Futura, however, has been designed to give absolutely zero side-play, this is because the sliding bearing system and the bearings the blade holder rotates about are all ‘pre-stressed’ so there is no possibility of unwanted movement between the blade tip and the cutter bar of the machine.

Lastly, make sure the board is being clamped properly and check the surface you have the cutter on is flat and not bent or twisted.