non-starting arc comes from dirty steel surfaces, Clean with acetone thorough before welding, My Lincoln starts reliable now, Check ground clamp condition.
Arc failure comes from bad contact or grounding, Check tip for wear or damage, My PowerMIG 260 failed to start too, Clean tip with alcohol, Set wire speed to 230 ipm, Use 20 CFH argon, Set voltage to 22V, Tighten all connections.