Ok,

The story is my alternator sometimes charges, sometimes doesn't.
After struggling with it for a few weeks I gave up and went back to the shop where i got my alternator replaced at.
The guys inspected the unit and said my alternator looks to be in great condition. It was putting out 14.4 strong.
I kept telling them about the failure to charge sometimes and suggested a brush problem like a few members of BB have hinted at.
The mechanic told me that if indeed my brushes were worn out, then it would not charge at all, unlike my situation where it eventually does charge.
He told me it would be a waste of $60 labour to yank the entire unit to find nothing wrong and to wait till the whole unit fails and then bring it back to them.
Obviously I don't want to be stranded with a dead alternator in the middle of the night, and the problem seems to be getting worse.

Looking back on the previous repair invoices over the years for this car, I notice that past alternator problems that were fixed by the dealership involved the replacing of a fuse. (This car is a hand me down, and my dad said that the alternator was never replaced, but the dealership did something and the car would charge fine afterwards)

Is there a fuse that I don't know about that could be causing this problem?

In one of my other posts someone suggested a test for the wiring harness for the alternator lead. The red wire that goes from dash to the alternator, is this a wire that needs to be grounded for the light to illuminate? How would I test to see if its grounded? Use a test light or something?

Million thanks.