Hello Ed,
I want to say this in the nicest possible way, Well, how about this;

You certainly have enough penetration, so a lack of power isn't the issue,

But by the very pitted looking finishes on the beads you have some contamination issues, I'm guessing rusty wire, or bad shielding, or both, the beads look a bit sharp on top which indicates maybe a little too much wire feed. Supporting these opinions is the evidence of quite a lot of spatter, dirty liners, too much power and too high a wire feed will cause spatter.

In terms of shielding I'm going to guess you are flowing enough gas at 20 l/min but possibly holding the torch at the wrong angle if the torch is lying too low air can be pulled in by venturi effect, so rather then trying th run full beads hold the torch near to perpendicular to the base metal just to see if the weld comes out cleaner.

As far as contamination goes, if someone has used your machine with really rusty wire the liner might still be holding enough rust and dirt that it is this residual dirt contaminating the weld, try to blow the liner out with compressed air or replace it with a new liner.

So,
Try these tips;
Clean out the liner,
use only enough power to discolour the reverse side of the plate, not enough to show weld bead through the reverse surface,
adjust the wire feed so that the bead height is between 1/3rd and 1/4 of the bead width and move the torch at a speed that matches the welder's ability to create a stable weld pool at the chosen settings.

I hope this helps,
Regards
Rick