MULFINGEN, Germany (AP) — Germany needs a new business model. The old one, fueled by cheap natural gas from Russia and lucrative exports to China, is broken, leaving Europe's biggest economy mired in stagnation and angst about the future. Delivering that fresh growth strategy is going to be the biggest challenge for the government that takes office after a national election set for Feb. 23, seven months ahead of schedule. The nation that became known for the quality of its products has not seen real economic growth for five years. Multiple factors conspired to take Germany from industrial powerhouse to…