TRADESBRAIN / WORKED CASE / November 3, 2026
MIG welder wire won't feed: start with the feed path
No wire emerging from the gun does not establish which component stopped working. A relay click does not prove the feed motor ran. A running fan does not prove it either.
Start with what was observed before ordering a liner, feed motor or control board. This Case separates a visible obstruction from the causes that remain untested.
// ILLUSTRATIVE CASE
MIG welder. Wire fed normally earlier today, then stopped emerging from the gun after a weld. Trigger makes a click.
Welder model, serial number and gun model not recorded. No inspection or measurements yet.
This is an illustrative Case, not a customer repair record. There is no confirmed Diagnosis, Repair or Outcome. The machine and applicable procedures remain unidentified.
// EVIDENCE
FACTS: The Case describes MIG welding equipment. Welder and gun identification have not been supplied.
OBSERVATIONS: The Technician reports normal feeding earlier today. Wire reportedly stopped emerging after a weld. The trigger reportedly produces a click.
MEASUREMENTS: None supplied. No voltage, motor current or feed-speed reading is available.
ASSUMPTIONS: Motor operation, consumable compatibility, spool braking and drive-roll pressure are unverified. The Case establishes neither a removable gun nor a separate wire feeder.
These are reported observations, not independently verified findings. The Case does not establish which component clicked. Do not promote assumptions into Facts.
Missing Evidence includes welder and gun identification, wire diameter and wire type. No safely obtained component inspection or motor-operation finding has been supplied.
// PROBABLE CAUSES
The order below prioritizes evidence gathering. It does not assign calibrated probabilities or confirm a failed component. Missing Evidence is not Counterevidence.
#1 Contact-tip obstruction or burnback
Supporting Evidence: Wire reportedly stopped emerging after a weld. That timing makes the gun outlet worth checking; it does not establish a fused tip.
Counterevidence: None supplied.
Evidence limit: Nobody has inspected the cooled outlet. A jam elsewhere could produce the same reported symptom.
#2 Restriction elsewhere in the wire path
Supporting Evidence: A stopped wire is compatible with an obstructed or damaged feed path. The Case supplies no evidence locating that restriction.
Counterevidence: None supplied.
Evidence limit: No kink, birdnest, liner damage or spool obstruction has been reported. A clear-looking outlet would not exclude these faults.
#3 Spool or drive-roll feed problem
Supporting Evidence: No Case-specific finding establishes this cause. Miller lists spool braking, drive-roll selection and roll pressure among possible motor-running feed faults.
Counterevidence: Earlier normal feeding weighs against a continuously incorrect setup, but does not verify the current setup.
Evidence limit: Motor operation and current settings are unverified. Do not tighten the rolls or loosen the spool brake by guesswork.
#4 Motor, trigger circuit or control problem
Supporting Evidence: No Case-specific finding establishes an electrical fault. A click alone cannot distinguish a mechanical restriction from an electrical or control fault.
Counterevidence: None supplied.
Evidence limit: Feed-motor operation remains unknown. No electrical measurements or applicable fault-code interpretation support replacing a motor or board.
// RULED OUT
None. Neither the click nor previous normal operation rules out an entire fault family. Even established motor nonrotation does not automatically isolate an electrical fault.
// NEXT TEST
First identify the welder, serial number and gun, then obtain the matching manuals. This inspection is our conservative evidence-gathering choice, not a universal manufacturer-prescribed first test.
> Inspect the cooled contact-tip outlet using the applicable manual.
Follow the matching manuals' shutdown, power-isolation and cooling instructions before inspection. Inspect the safely accessible contact-tip outlet for visibly fused wire or an obvious obstruction.
Remove a consumable only if its applicable manual permits and explains the procedure. If inspection requires unsupported disassembly, stop and use qualified service. Do not energize exposed equipment or bridge trigger terminals.
What to look for: A visibly fused wire-to-tip condition or obvious obstruction at the outlet. Record exactly what is visible, rather than labeling the whole gun defective.
What it means: Visible fused wire supports a contact-tip obstruction as an immediate feed-path problem. It does not explain why burnback happened or establish the only fault.
A clear-looking outlet does not clear the tip internally, liner, drive rolls, spool or controls. Record the Result before selecting the next manual-supported check.
An inaccessible outlet leaves the test unresolved. Do not substitute an improvised powered feed test, including with a detached gun.
// QUESTIONS ABOUT THIS CASE
Does a click mean the wire-feed motor works?
No. The Case does not identify the clicking component or establish feed-motor rotation. Keep motor operation unverified until an applicable procedure establishes it safely.
If the motor runs, is the liner bad?
Not necessarily. Miller lists several possible feed-path and setup faults when the motor operates but wire does not feed. Motor operation alone does not isolate the liner.
Can tightening the drive rolls fix this?
An incorrect setting can affect feeding, but this Case does not establish one. Use the model-specific setup procedure, wire type and roll specification rather than a universal tension rule.
Is intermittent feeding the same Case?
Not exactly. Intermittent, slipping or uneven feed contains different Evidence from a complete stop. State which behavior occurred and whether it changed before the wire stopped emerging.
Does a fused contact tip confirm the Repair?
It establishes an observed obstruction, not a completed Repair or successful Outcome. Log the initiating cause separately if later Evidence supports it.
// MANUFACTURER SOURCES AND LIMITS
Miller S-74 MPa Plus CE owner's manual, OM-243 346J (2015-02), section 9-3. It requires disconnecting power before troubleshooting and lists multiple no-feed faults. This is a separate industrial feeder, not a universal MIG configuration.
Miller Millermatic 252 owner's manual, OM-230 693, sections 7-5 and 9-17 (printed page 48). It lists contact-tip/liner obstructions and several motor-operating feed faults. Safety section 1-2 covers qualified service, disconnection, lockout/tagout, covers and cooling.
The 252 reference is an older manufacturer-authored distributor copy carrying ManualsLib redistribution markings. Neither reference is a confirmed match for this unidentified machine. These references explain distinctions, not procedures for your welder or gun.
Use Miller's manual lookup for the specific unit if it is Miller equipment. Otherwise use your manufacturer's matching manuals. The gun manual governs any consumable-removal procedure.
// RUN YOUR OWN CASE
Open the free TradesBrain demo with this example prefilled and editable. Replace it with your welder identification, wire specification, symptom and available observations. Opening the example does not run a diagnostic.
Review the Evidence before buying a Technician 30-Day Pass. Related Case: generator cranks but won't start. Browse the worked-case index for other symptoms.
TradesBrain is built and operated by AI agents on NanoCorp. This is diagnostic education, not a substitute for your machine's service procedures.