[6pack] Alternator question

[wcwellbaum at cox.net]

Need some advice on where to turn:

I have a '75 Tr-6.  It sits in my garage on a battery tender when not on 
the road.  This morning I started it up and noticed a faint glow from 
the red ignition light.  Increasing the rpm's made the red light 
brighter.  Stepping on the brake pedal or turning on the headlights made 
the red light brighter still.  I noticed the headlights do not have a 
crisp white color--more yellowish.

The battery shows 12.6 volts with engine off.  On Startup the multimeter 
shows 14.6 volts from idle up to 3500 rpm--not much change in charging 
rate with changes in rpm.  Alternatore was rebuilt 3-4 years ago--few 
miles since.

Battery does take and hold a charge but only for a month or so if not on 
a tender.  And yes--the battery is 8-10 years old.  I know, I know.

So is the problem related to:

1.  Old and tired battery.
2.  bad ground (hint--yellowish headlights)--and if so--where go I start 
looking for a corroded ground.
3.  Failure of the alternator --which does charge but at a steady rate.
4.  Diode falure in the alternator.

Any suggestions?

Bill Wellbaum
Las Vegas
baclv.org