Techmarine

The army may have up to 3 Servitor models operating support weapons per Techmarine that is in the army

Repair - May attempt to repair a single damanged hit location on a vehicle, a Dreadnought , or a destroyed support weapon, if he can reach it during his next movement phase. He can do nothing else during the turn - he cannot shoot or fight in close combat while he is attempting a repair. At the end of the turn roll a D6:
5-6: Repair. Repair all damage sustained in the previous turn.
3-4: Possible Repair. Damage is not repaired this turn, but you may carry on working for a further turn if you wish. At the end of the further turn the damage will be repaired on a roll of a 4+. If failed, the damage is beyond repair. May do nothing else while repairing
1-2: Hopeless. Not possible to repair