I've had good luck previously using my 3m radial discs to polish
my work after sanding, but it isn't working now.
are your radial disks getting a bit worn? Especially if you use them
with more than slight pressure, they can get “dulled”. Properly,
only the tips of the bristles should contact the work. If you press
harder, it works at first, but the bristles are then wearing down on
the flat sides of the bristles, not the tips. That makes them thinner
and reduces their effectiveness.
On the other hand, if you’re having these reduced results using new
bristle disks when new ones before worked, I’d suggest looking at
whether the metal is annealed the same way, and whether whatever
steps you take before and after the bristle disks is the same.