Steve Gagnon has been in the repair business for the past 30 years, seven of them with Steve's Shop in Charlestown. The business services diesel engines and is an authorized service center for John Deere Marine, Northern Lights Generators, Lugger Marine Propulsion, Yanmar Marine Engines and Kohler Marine Generators. When it comes to welding and fabricating, the shop works with all aluminum alloys, stainless steel and aluminum boat repairs. Walk-ins are welcome, but Gagnon said it's best to give him a call before dropping by. Steve's Shop is located in the Boston Autoport, a fenced-off location with security guards.