Black spots comes from poor surface prep or gas issues, Clean steel with acetone before welding, My YesWelder MIG-205DS had same issues, Use 25 CFH argon for proper coverage, Check for gas hose leaks, Set wire speed to 240 ipm for consistency, Use 7018 electrodes for cleaner welds, Ensure clean joint fit-up, Use wire brush for prep, Verify regulator settings.
