We have just had the ‘alternator on the way out’ experience. Symptoms were the buzzer not going totally silent on engine start and, when I looked closely enough, the domestic alternator warning light was glowing faintly. I took the old alternator to Electrostart in Daventry, who ran it up on their test rig and confirmed that it wasn’t working properly.
They gave me the option of them rebuilding it, fixing the failed diode pack and whatever other problems they found, or just buy a replacement, which would be quicker and cheaper. They transferred the pulley from old to new, checked I had the right electrical connections, and altered a fixing point on the alternator to suit the bolts I had. Friendly people, excellent service, and the only retail place I have ever seen left hand twist drills on sale!
Recommended.
https://electrostart.co.uk/