I had a galling issue on one of my chokwes before too. It just happens with Ti on steel. Graphite will work, but sometimes it takes multiple applications. Its important to take care of it as soon as you notice sticking because each time the lockbar sticks and you force it out you're exacerbating the issue.
Use sharpie, graphite, or some sort of dry lube. Liquid lubricant will not help. In fact, if you overlube the pivot and don't wipe the lock interface totally dry that's often what will start the galling in the first place.
As I understand it, a galling lockface is being deformed on the microscopic level each time it is unstuck. I believe the graphite acts as a lubricant to prevent further galling and repeated actuation of the lock will smooth the surface back out. If the galling is somewhat bad it takes more applications of the graphite because it takes longer to smooth out the surface. I'm no expert on this though so someone please correct me if I'm mistaken.