I've figured it out. There are two separate bolts. One for the neutral indicator signal that threads into the neutral stopper itself (3mmx1.0), as well as the retaining bolt (6.0 x 16 x 1.0) which screws into the case itself along with the "D" washer which acts as insurance the neutral stopper does not slip out. Can't believe it took me this long to realize there were two separate bolts at play here. Man.