Fix the support generation for the thumb clusters

This fixes the generation of screw supports for the thumb clusters in the
steel base full assemblies

lalboard.py

@@ -2308,7 +2308,7 @@ def add_thumb_standoffs(self, thumb_cluster):
         down_normal = front_magnet.bottom.get_plane().normal
         ball_magnet_radius = self.ball_magnet().size().z / 2
         down_normal.normalize()
-        down_normal.scaleBy(-ball_magnet_radius)
+        down_normal.scaleBy(ball_magnet_radius)
         ball_magnet_center_vector = down_normal
 
         cluster_transform = thumb_cluster.find_children("thumb_cluster", recursive=False)[0].world_transform()