The Singer 404 is a classic straight-stitch sewing machine known for its durability and reliability. This service manual provides comprehensive information for maintenance, troubleshooting, and repair of the Singer 404 model. It includes detailed sections on machine specifications, disassembly and reassembly procedures, timing adjustments, lubrication points, common issues, and parts identification. Below are key sections for safety, features, maintenance, operation, and troubleshooting.
Key components: Cast-iron body, straight-stitch mechanism, built-in bobbin winder, reverse stitch lever, stitch length regulator, tension dial, and presser foot system.
| Feature | Description |
|---|---|
| Stitch Type | Straight stitch only |
| Stitch Length | Adjustable via dial (0-4 mm) |
| Reverse Stitch | Lever-activated for back-tacking |
| Bobbin System | Class 66 metal bobbins, drop-in style |
| Needle System | Singer 15x1 (standard domestic) |
| Motor | Built-in electric motor with foot control |
| Tension Control | Front dial for upper thread tension |
| Presser Feet | Standard snap-on feet compatible |
| Weight | Approximately 25 lbs (11.3 kg) |
| Power Source | 110-120V AC, 60Hz (US model) |
Always unplug the machine before performing any maintenance or repair.
WARNING! Never operate the machine with covers removed. Risk of electric shock or injury from moving parts.
Follow these steps to access internal components. Always keep screws organized.
Note: Take photos during disassembly to aid reassembly. Lubricate parts before reassembling.
Proper timing ensures needle and hook interact correctly for stitch formation.
Tip: Use a timing light or magnifier for precise alignment.
Regular lubrication reduces wear and ensures smooth operation. Use Singer sewing machine oil only.
| Location | Frequency | Notes |
|---|---|---|
| Hook Race | Every 8 hours of use | 1-2 drops |
| Needle Bar | Monthly | Oil at top and bottom bushings |
| Bobbin Case | Monthly | Light oil on moving parts |
| Gears | Every 6 months | Apply sparingly |
| Motor Bearings | Annually | Consult motor manual |
CAUTION! Wipe excess oil to prevent staining fabric.
Correct needle and thread setup prevents thread breakage and skipped stitches.
WARNING! Always use correct needle type (15x1) to avoid damage.
Balanced tension creates even stitches on both sides of fabric.
Note: Default upper tension setting is 4 for medium-weight fabrics.
Quick reference for frequent problems.
| Issue | Likely Cause | Solution |
|---|---|---|
| Thread bunching underneath | Incorrect bobbin threading | Rethread bobbin, check tension |
| Skipped stitches | Blunt needle or incorrect timing | Replace needle, check timing |
| Needle breaks | Wrong needle size or bent needle | Use correct needle, insert properly |
| Machine jams | Lint buildup or thread jam in hook | Clean hook area, remove thread |
| Uneven stitches | Incorrect tension | Balance upper and bobbin tension |
Key replacement parts for Singer 404. Refer to official Singer parts diagram for full list.
Note: Order parts from authorized Singer dealers or www.singer.com.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Machine won't start | Power cord, foot control, or motor issue | Check power outlet, test foot control, inspect motor brushes. |
| Noisy operation | Lack of lubrication or worn gears | Oil moving parts; inspect gears for wear. |
| Thread breaks frequently | Rough spots on needle or thread path | Replace needle; check for burrs on guides. |
| Fabric not feeding | Presser foot pressure too low or feed dog clogged | Adjust presser foot pressure; clean feed dogs. |
| Light not working | Bulb burnt out or wiring issue | Replace bulb; check wiring connections. |
Reset: For persistent issues, complete disassembly, cleaning, and reassembly with lubrication.
Service: For professional repair, contact Singer authorized service center at 1-800-4-SINGER or visit www.singer.com.