In this application it isn't about how well they attract steel objects (like your screwdriver tip), but about how well they disrupt the coil's field. If the spark is good, the magnets are good (or "good enough").
And, as stated, magnets hold their charge a VERY long time. About the only things that can really mess them up is shock or heat. If the flywheel wasn't dropped or torched, it is more than likely just fine.
Of course, if your spark is week and you know the other components are fine, then you may need to re-mag.
Last edited by NJ-boatbuilder57
on Fri Dec 01, 2017 9:36 am, edited 1 time in total.