Most post war flywheel magnets were made of Alnico alloy which maintains its original magnetism much better than the pre war iron magnets which can lose theirs over time or from shock and will then require a recharge. Early flywheels should have a piece of steel or iron placed across the magnets poles to help retain the magnetism whenever the flywheel is removed. Not so much with the Alnico magnets. No flywheel should ever suffer shock, as when being struck with a hammer.
I tried for several years to find a Stevens brand magnet charger but gave up and built my own. It’s a Gingery design but is similar to a Stevens unit.
Here’s a link to an older post here about magnet chargers and it also includes a YouTube vid of a Stevens charger being used.
https://aomci.org/forums/topic/recharge-magnets-on-fly-wheel/page/2/
