I Usally run a millermatic 212 set up with .035 hard wire and a 75/25 argon co2 mix at work. Works great but every once in a while i'll have to run flux core because I'm outdoors. I reversed the polarity, put in knurled drive wheels and put in a fresh liner. Now comes my problems. 1 as I'm welding the wire will just stop feeding. usually with mig i just flick the lead and the wire will pop out. With FC the wire gets all rats nested inside the machine. I loosened the clamp on the wire and make sure I have a new tip but it still happens mid weld instantly. This happens once in a while running mig but with FC it's like every half hour. Any ideas would be greatly appreciated. My other issue is on thinner steel I'm getting holes in my welds. kind of like perosity i guess. When i run mig I can use the same tip all day, FC i'm using about ten.. Is this typical of FC?