My alternator belt was replaced recently. The tension is ok on the belt. However since the replacement, the alternator light and Oxy light turn on when the RPM goes below 1500 RPM and turn off when RPM is above 1500 RPM. I didn't have time yet to check if the voltage is still 13.8 volts at the battery when it is happening. Could it be the brushes on the alternator? Any idea why it is happening after the belt was replaced?

Germain