I recently went over the installation instructions for the Hipshot BT-1 Bass Xtender / D Tuner for my musicman bass which I bought off of a user on this site. Step #4 on the installation instructions say, "Reassemble tuner being sure that the nylon spacer washer (and BT-1's spring tab) is in place." What is the spring tab? There is not part in pictured in the instructions called "spring tab". Any one have any idea what this is?