64C charging issues

[BK911]

64C with 12V conversion
Gen warning light came on at low rpms.
Grounded Df and had >13V at D+
Swapped out VR with used spare.
Now Gen warning light comes on at high rpms.
V at D+ was 4.8@500, 6.5@1000, 12.3@1500, 14.3@2000, 13.8@2500 and bounced around too much to measure at higher rpms.
Brushes stick out maybe 2-3mm past the holders.
Nice grooves on the "thingy".
Used sand paper on the thingy with engine running to clean it up.
Not sure what to do next???
Replace VR with a new one?

Wasn't a big deal until I had to start using the headlights on the way to work.

Thanks!
BK