In our game yesterday one of my ships reached level 6 on the impulse critical track. By our reading of the rules, at this point the impulse critical track no longer escalates, since there are no more levels of critical hits to reach, but all future critical hits to this location cause 2d6 damage (the extra damage from the level 6 critical). Just wanted to confirm that escalate doesn't cause extra damage if the ship already has 6 criticals in that location.