Disconnect ground wire from battery.
Remove ignition coil cover. Disconnect the spring with a wide screwdriver, slightly press the cover and turn back.
Remove the connections from the ignition coil.
If the plug is pushed out (see arrow) on the ignition coil, then replace the coil.
Check the resistance of the primary winding of the ignition coil by connecting an ohmmeter to terminals 1 and 15.
Check the resistance of the secondary winding by connecting an ohmmeter to terminals 1 and 4.
Connect the wires to the ignition coil.
Place the cover at the back, press and snap forward. Check the correct places for the wires on the cover, use pliers to clamp the cover at the bottom.
Connect ground wire to battery.
Attention: If the ignition coil is being replaced, then under no circumstances should a coil be installed for a conventional contact ignition system. This can damage the switch.