There is not much there right now, but I think I have succeeded. :)
This is Good Tension
Check out the dents/pattern in the filament. See the crosshatch pattern from the knurled bold? That is what good tension looks like.
Here is another shot of the good tension. I read that you want enough tension to create the crosshatch pattern, but not so much as the deform the filament.
One More Shot
Here is a third shot. It seems that tighter is better, but not too tight. The goal is to allow the feeder to overcome higher frictions and deal with retractions, without grinding the filament. The last third of a spool, for example is harder to pull, then the start of it.