Heres a couple shade tree troubleshooting tips to help isolate should a no charge condition occur out on the road far from your tools/shop/garage. That said HRM's above technique should be used for proper troubleshooting and repair.
With the engine running at fast idle or higher, remove the brush access cover from the generator (generally a strap), you should see atleast one of the brush assembly's on the top side. With a stout wooden stick, gently push down on the brush to force it to have better contact with the commentator. If the brushes are worn down or some grit of grime gets between the the brush and commentator this may get it charging. It may work good enough to get you home where you should repair the generator.
Sometimes the BAT, field or armature contacts in the regulator can stick. With the engine running at a higher than idle RPM, gently tap on the regulator to see if it starts charging. If so like above it may get you home. You'll need to clean & check the adjustment on all three regulator contacts.
Course make sure all your electrical connections are clean and tight, 2 at the generator and 3 at the regulator.
Good luck
Dave
