1010 generator testing

I just had my 1010 generator (2 brush) rebuilt because the F pole terminal insulator disintegrated and the wire broke. I reinstalled it today and want to make sure it was rebuilt right. I had the tractor running at ~1200 RPMs. When I measured the voltage across the F & A pole, I was only getting about 8volts. i was expecting 13 or more. Could they have rebuilt it for a 6volt system or is that OK?