Genny, Third brush!

[Terry, NJ]

Well my Genny works fine , when it works! How do I get it working? Well I have leave the band off and take a screw driver and manually push the adjustable brush onto the commutator' when I see some sparks, I know it's charging again. Sure enough, a glance at the ammeter shows about 8 amps. Howcum? I've sprayed it with WD40 , but the arm seems free, It's a new brush, so it's not the length of the brush.
Terry