Alternator Question

[eric.schnettler@domain.elided]

My 88 Graduate has both a voltage meter and an alternator "idiot light" on
the instrument panel.  When driving at night I've noticed a (very) faint
red glow of the idiot light.  Additionally, the voltmeter indicates around
11 volts.  If I crank up the radio volume and hit the high beams I get a
somewhat brighter red glow (but not the blazing "on" red like when you
first crank the engine during an engine start) from the idiot light.  At
high RPM I see a slight drop in voltage and at idle I have a higher
voltage.  I'm assuming the drop in voltage at high RPM is caused by the
ignition system placing more of a load on the alternator than at idle but
this is just my guess.
  It seems to me that the instruments are indicating a "real" alternator
problem.  Can this be remedied by replacing the brushes in the alternator
or does this warrant a new/rebuilt alternator?  I'd be interested in
hearing anyone's opinion or experience with this.

Thanks
Eric Schnettler

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