ETOWAH, Tenn. — ThyssenKrupp Waupaca Inc. officials this week declined to comment on a lawsuit claiming that workers at three Waupaca foundries, including one here, are owed back wages and overtime pay. Mitch Quick, an attorney for the company in Milwaukee, said his firm has “looked over” the lawsuit but has not filed an answer. “We believe the lawsuit is without merit,” Mr. Quick said, adding that the…