dmsog

You can actually clean the rings and check them for concentricity without disassembling the alternator. Clamp the alternator in the vice by the thick mounting leg and reach in with 600 paper and apply pressure to the rings while spinning the pulley. This will take a while, but will get the job done. If your finger moves up and down while spinning you have a real problem.
The brushes are soldered to the regulator. Unless you are good with soldering equipment and have access to a set of brushes, you're better off replacing the regulator. I have brushes, but I don't think I'm supposed to advertise here, so disregard that statement.
Be sure the rings are also not deeply grooved. You'll be able to see this after you remove the regulator.
Doug

dme

So theoretically if someone was tearing into that part of the engine AND planned to remove the alternator AND they had 158K on the car AND they had no indication the alternator had ever been serviced then it might be a good idea to do a little preventative maintenance. Besides that, I'm a man and a 944 owner so I obviously must like to tear things apart. In fact, I'm so good at it that I can often put these things back together again and have extra pieces laying around.

So how much does a set of brushes and/or regulator cost?

And who says you can't 'advertise' here? This is my first stop for knowledge and parts.

IceShark

They are cheap, under $20 for the regulator with the attached brushes. I sell them for $21 with the shipping.

Since a new regulator is so cheap I don't think it would be worth your time to unsolder the old ones, bend some metal out of the way and solder in new brushes. Plus, I would opt for an adjustable voltage regulator which you may not have.

But I'm certain that your alternator has had something done to it if you have 158K on the car. The original brushes would be worn down to tiny nubs by now.