Dimming lights...bright lights...dimming...bright...

And of course, both the alt and reg are new.
The reg cost me $50+ as I got the better one that Dan suggested, the alt was a reman- could that be the issue?

How do I replace the brushes?

I kept the old alt, which is a reman as well and was hurting, at least by the looks of it. Maybe I'll switch them and see what happens.

I also have a new replacement reg that I can swap and see if that works.