Alternator warning light

[simmitc]

A standard Minor, alternator from new. Appears to charge OK (volt meter says 13.8 volts) but form time to time the warning light glows very slightly. It's not on full, just a faint glow, and only intermittently. Any suggestsions as to what might cause this would be greatly appreciated. Thanks.

[bmcecosse]

Belt slack? Or just worn down in the groove? Try a new belt! Could be the brushes are getting worn and losing spring pressure - actually just the ONE brush that runs on the ring contact - the centre brush hardly ever wears away.