Step 12. Install the small optical sensor support bracket on the bottom screw hole and attach the ground wire you moved out of the way on step 8. The first photo does not show the ground wire attached. Do so before you go on to the next step. Step 13. Install the trigger wheel on the shaft paying close attention to the flat sides on the shaft and the matching flat sides inside the trigger wheel. Step 14. Install the optical sensor to the support bracket from step 10 and check for proper spaci