My MIG welder

I got this CIGWELD WeldSkill 150 second hand late last year. The wire speed control is infinitely variable (you can set it to 7.75 for instance) but the voltage control has detents which allows only 4 settings. The machine works very well for 1/16" thick steel and thicker. However, I still can't get it to properly weld thinner gauge sheet steel. I can't get good continuous welding with wire speeds lower than #7 even with voltage turned down to its lowest setting of #1. Not yet sure why.

Auto-darkening helmet in the background and an AC stick welder which I haven't used in months

Load with a new spool of 5kg 0.9mm flux cored wire

Red and black wires need to be swapped depending on whether you're using flux cored or solid wire

Flow meter for the shielding gas when I'm using solid wire. The masking tape with blue mark indicates the 10 liters/min (equiv to around 20cfh) level. Did this to make sure I don't set the flow incorrectly. I'm using 80% argon 20% CO2. Can't find 75/25.