Flickering or pulstating Headlights

MopaR&D said
When the engine is running above idle the voltage will pulsate between about 14-15 and I can see my dash lights and headlights flickering with it

Could be ripple voltage or a regulation issue.
Also possibly a poor connection or loose plate etc.

superchargeddrt said
Try revving the engine and see if it still flickers. If it does then I would suspect the alternator.

This is a good check.
Also, what is the voltage at idle? and is it steady?
How 'bout with lights on?

MopaR&D said
By brush connection on the alt do you mean one of the field wires or the main wire?

Yes and no.
You can see what the brushes in post 15: Alternator repair, a little show and tell.
In the photo below you can see where the brushes come through.

(The yellow arrow points to the output stud. If its loose it needs to be snugged up from the inside.)
The two copper rings on the rotor is what the brushes contact.

When electricty flows through the rotor windings, it creates a magnetic field. That's why the brush connections are called field terminals.