BEFORE YOU DO ANYTHING ELSE!
Back-check the dashpanel voltmeter using a quality diagnostic voltmeter - those dashboard things are notoriously inaccurate, and the connection may be getting shonky. Mine wanders between two volts low and two volts high (I haven't bothered to figure that one out - I get a rock solid 15VDC, as checked each month, so I'm not worried about it.) I'll address that little problem when I finally redesign the gage cluster, since I'll be going to mostly aircraft gages anyhow (what do you expect from a former pilot?)
If the voltage check fails, check belt tension, and make sure your power steering pump isn't on the fritz. A failing power steering pump will often cause belt glazing and/or slippage, which will adversely effect alternator output.
If that's all good, get a new alternator. There was a lot of issues with it when I posted (all political, don't worry,) but I got my builder to post in Classifieds. You can call him if you don't like Mean Green's pricing...
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