A-B1797343-AI ARMATURE-MAGNETOOne New Aftermarket Replacement Magneto Armature (Ignition Coil) Fits Briggs & Fits Stratton Engines This aftermarket replacement magneto armature serves as the solid state ignition module in Fits Briggs & Fits Stratton small engines. Mounted adjacent to the flywheel, the armature generates the high voltage pulse that fires the spark plug on every engine cycle. A failed or weak armature is a common cause of hard starting, misfiring, or no spark