You need a feeler gauge, between the electrode and the ground bar should be .025", most small engine plugs come pre-gapped to around that. As long as it's not over .030.
The magnet is the part in the center of this picture, it should clear the top and bottom, slip a business card in between, if it fits, you're good. To adjust it, loosen the four screws and move the coil around until there is a gap on both sides.
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