Older Bolens tube frame's used Battery Ignition Switches. Todays electronic control engines use Magneto Ignition Switches. From my understanding "B" battery ign sw shuts off power to the coil which stops spark whereas "M" ign sw grounds out the coil packs at the switch to shut down. I have read these switches are not interchangable - ( "B" shuts off / "M" grounds out) . Is my understanding correct or somehow these 2 types of Indak switches are interchangable??