[Vwdiesel] bad alternator?

[Chris Jude]

Folks,

I tightened up the belts on my 85 VW Jetta earlier this week, and have been
having battery issues since.  The alternator had performed well, though the
belt has l;ong had a tendency to get a little loose every few weeks.  The
only odd thing I noticed was that while tightening the belts I tapped the W
connection on the back of the alternator and saw a small spark.  Also,
there are three wires on the + post of the battery, one to the starter, and
two to red 8ga wires that go to the drivers compartment.  One of these two
red wires will spark a little when I remove it from the post.  These wires
all have some new corrosion on them, which I cleaned off a couple days ago.

The battery light is coming on now, and the battery is not recharging.  I'm
able to drive to work in the am with the lights on without totally losing
juice, but am recharging it in the day.  This evening when I got home the
battery was at 12.0V.
I replaced the wires to the alternator this evening with no noticeable
results.  I am not seeing any charge from the alternator with the engine
running at idle or up to full rev.
Any tips on what to check next?  Could I have shorted the alternator by
tapping the W post?

Thanks,
Chris Jude
Silk Hope, NC