Welding woes...frustrating!!

If your budget allows I would get a non flux core mig welder I have a mig 175 from eastwood. I run .023 to .025 wire on a 220 outlet. I had a problem when using the thinner wire. It wouldn't feed properly I needed to get a knurled roller. Maybe the machine isn't feeding the wire properly or not at proper tension Just a suggestion
It doesn't seem to fees right but I double checked everything and when I'm not welding the wire feeds just fine it just seems to slow down during welding. It very possibly could be because im using an extension cord to run the welder. I'm using the size cord it called for in the manual but maybe its loosing to much juice in the cord