We can rotate the layer mask to disguise the repeating pattern in the effect.
- On the layer's palette, click the chain between the thumbnail for the stamp graphic and the layer mask to unlink the mask from the layer.
- Click on the layer mask thumbnail.
- Press Ctrl-T to enter free transform mode.
- Rotate the mask slightly until the repeating pattern is less obvious.
The beauty of layer masks is that it enabled us to correct this mistake without starting over. If we had used an ordinary selection we would have had to rotate it earlier in the process and it would have been permanent. If you didn't catch the problem at the time, you would have had to go back and redo several steps.