Arty captains hardcoded to slot 4.

src/engine/objects/NPC.java

@@ -356,6 +356,9 @@ public class NPC extends AbstractCharacter {
 			if (slot == -1)
 				Logger.error("No available slot for NPC: " + this.getObjectUUID());
 
+			if (this.contract.getContractID() == 839) // Arty Captains are hardcoded to slot 4
+				slot = 4;
+
 			building.getHirelings().put(this, slot);
 
 			// Override bind and location for  this npc derived