To fix this, move the horizontal sync pulse. That is, increment or decrement (by a multiple of 8) the middle two numbers of the horizontal timing section that define the leading and trailing edge of the horizontal sync pulse.
If the image is shifted left (right border too large, you want to move the image to the right) decrement the numbers. If the image is shifted right (left border too large, you want it to move left) increment the sync pulse.