U.S. Rep. Seth W. Moulton?s vow to repeal a medical device tax spells good news and potential job creation for North Shore firms like Analogic in Peabody, an industry spokesman said Thursday.?We feel Cong. Moulton understands the issues facing his district,” said Massachusetts Medical Device Industry President Tom Sommer.Moulton travels Monday to Danvers medical device maker Abiomed, where he will explain why he is co-sponsoring legislation to repeal the 2.3 percent medical device excise tax.During his congressional campaign last year, Moulton called for repealing the medical device tax, noting “it?s not the Democrat position, but it needs to be done.”Sommer said makers of devices ranging from surgical instruments and sophisticated hospital equipment to prosthetic implants have pushed since 2009 to get rid of the tax. Companies are taxed throughout the year on their total revenue.?You can be non-profitable and still have to pay the tax,” he said.Implemented in January 2013, the tax, said Sommer, hurts a Massachusetts industry that is a leader in exports and generates business for medical device suppliers and other, smaller firms. Sommer said savings realized by firms if the tax is repealed can be spent on research and plant expansions.?This is hitting an industry that is dealing with a lot,” he said.He said 400 medical device makers are in Massachusetts, including big firms like Analogic and Abiomed, Inc., where Moulton will speak on Monday at 10:30 a.m. along with device industry executives. The industry employs 23,000 workers.