Quoted from bigehrl:Nick, this happens on my last 2 Sterns. The trick is to hold the button in as you're installing the lockbar, making certain the tip of the button's bottom is squarely on top of the white switch nub (don't know the technical term). once it's locked in place, release the button and it'll be good until the next time you remove it.
** DON'T go sanding or trimming anything!
This. 3 of my last 4 Sterns have done this.