This procedure works ONLY if the ratchet mechanism inside your caliper is working correctly. If it doesn't work correctly, your only choice (short of repairing or replacing the caliper) is to wait until the pads wear enough for you to remove the actuator lever and reposition it.
Here's the procedure:
1. Remove the actuator spring.
2. Ensure that the actuator moves freely, especially in the unlocked-to-locked direction. Loosen the nut holding it a bit if it does not move freely.
3. Make sure that the cable does not inhibit free movement of the actuator lever, and move it out of the way if necessary.
4. Move the actuator lever to the fully unlocked position (where it would be if the spring was there).
5. Step on the brake pedal hard.
6. Check that the actuator lever moved by itself from the unlocked position to the locked position. If it did not, loosen the nut a bit more so that it moves freely, and then repeat steps 4 and 5.
7. Move the lever back to the unlocked position, and then move it towards the locked position again. If it locks with only a little movement, you are done.
8. Repeat steps 4 and 5 if necessary.
When you are done, don't forget to tighten the actuator nut and replace the cable and spring.
