On the underside of the cutting head, you will find two grub screws (shown in red below), these screws set the position of the blade in respect to each other.

Before adjusting loosen the blade clamping screw for the relevant blade holder on the front of the head – only one blade holder will need adjusting.

Now adjust the relevant blade holder so that blade is in-line with the other blade. Please note: The adjustment screws only needs to be turned a very small amount to make a substantial difference.