MAG251 Parts Substitution Card

This is the quick external-parts substitution card for the highest-value MAG251 gun, spool-gun, and drive-roll splits.

Use This Card When

the arc is rough but the machine is not obviously dead
the complaint follows only one gun branch
feed direction or feed quality is under suspicion
chart-correct plain-steel base MIG has not cleared the complaint yet

Stage First

known-good plain-steel base MIG gun
known-good clamp and lead set
known-good spool gun only if the complaint is branch-specific
correct drive-roll family for the active wire and branch
chart-correct plain-steel baseline before spool-gun or post-service branch blame
feed direction confirmed before treating a post-service complaint like a random new fault

Fast Substitution Card

Complaint branch	Swap first	If the complaint follows the part...	If the complaint stays with the machine...
rough arc on base MIG	known-good base MIG gun and chart-correct plain-steel baseline	keep diagnosis in the gun and front-end branch	move to ripple and power-side logic
aluminum-only or one-gun-only failure	known-good spool gun and matching drive roll	keep diagnosis in the spool-gun branch	move back to the machine only if base MIG also fails
erratic feed quality	correct drive-roll family and wire baseline	keep diagnosis external and mechanical	move to feed-control branch only after the path is proven
post-service feed-direction complaint	confirm and correct direction first, then hold a known-good external branch steady	keep diagnosis in install or motor-direction logic if the external branch stays healthy	move deeper only after external proving is done

Official Ordering Shortcuts

MAG251 parts category: official parts path
SpoolKing24D spool gun 07NS1000: official product page
MAG251 drive-roll family including 072611011 and 07NS1005: official category page

Stop Rules

Stop if the complaint follows only the spool-gun branch.
Stop if drive-roll correction restores feed quality.
Stop if corrected feed direction removes the complaint.
Stop using the card and open the full guide if both base gun and spool gun still fail after external proving.

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