The Fire Department Special Hazards truck had to be towed from Station One last month and is still undergoing evaluation, Interim Fire Chief Peter McMichael said Monday. The truck was apparently overheating and has a “power issue,” the chief said. An older vehicle is taking its place. Meanwhile, the city is awaiting delivery of a new special hazards unit, which McMichael hopes will be ready in February. A grant will pay for that truck, costing about $800,000.