Charging problem

I have a 93 CVPI. The other day I was riding home and I noticed the voltage gauge on my dash dropped below "o" when driving. When I accelerated, it fluctuated up to the "r" and then dropped back when I started crusing. I got home tested the system. The battery wasn't charging. Connections were good, had no resistance between the alternator (130A) and battery (780 CCA). Fuse links measured good. Fuses good. Battery, a month old. Took the alternator out of the car, removed the voltage regulator and inspected the brushes. They looked low (3/32" and 1/8"). I suspected this was the problem but I had it tested. They said it was charging fine and sounded good. So I put it back in the car and it seemed to be charging fine.

Concerned about the conditions of the brushes being below spec (1/4"), I replaced them (BWD, 3/4"). I started the car and it was charging fine (14.7 V). I took it for a test drive (~6 miles). Came back home and tested the charging. It was reading 14.3(5) V and dropping slowly (~0.01 V per 2 min). I observed it until it reached 14.2(5) V and stopped dropping. The dash guage measured below the "r", which is unusual since it is usually on the "r" or higher. I replaced the voltage regulator, no change. 14.2 sounds a little low, but I don't remember the normal charging voltage.

Any ideas?

Thanks