Troubleshooting Common Juki MO-735 Problems – A Detailed Guide

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The Juki MO-735 is a versatile 5-thread serger and coverstitch machine that can handle a wide variety of fabrics and sewing tasks. However, as with any complex piece of machinery, occasional issues can arise that require troubleshooting.

In this comprehensive guide, we’ll explore some of the most common Juki MO-735 problems and provide solutions to get your machine sewing smoothly again.

Overview of the Juki MO-735

Before diving into troubleshooting specifics, let’s briefly go over what the MO-735 offers:

  • 2-3-4-5 thread serger stitching
  • Built-in rolled hem stitch
  • Up to 1500 stitches per minute
  • Color-coded threading guides
  • Removable cutting knife
  • Differential feed
  • Chainstitch and coverstitch capabilities
  • Sturdy construction for extended use

With this wide range of features, the MO-735 provides tremendous versatility for handling all sorts of sewing projects from garments to home decor. However, the complexity of the machine can also lead to occasional issues if not used properly.

Common Juki MO-735 Problems and Solutions

Here are some of the most frequently reported Juki 735 problems along with steps to troubleshoot them:

Fabric Not Feeding Properly

This is typically indicated by the fabric bunching up or becoming stuck. Potential causes and fixes include:

  • Incorrect presser foot pressure – Adjust the foot pressure dial so fabric can move freely but stitches don’t skip.
  • Wrong differential feed setting – Adjust differential feed between N and 2 depending on if fabric is stretching or bunching up.
  • Dull or misaligned cutting blade – Replace or realign the upper and lower knives for clean cutting.

Thread Breaking

Frequent thread breaks can quickly get frustrating. Here are some things to check:

  • Improper threading – Make sure all threads are following the correct path as shown in threading guides.
  • Thread tension too tight – Loosen thread tension dials slightly and test sew on fabric scrap.
  • Damaged or wrong needles – Replace bent, dull or wrong system needles. MO-735 uses 130/705H.
  • Fabric pulling – Don’t pull fabric while sewing, this can cause thread breaks. Gently guide it.
  • Debris or burrs – Check for any lint or snags along thread path and remove debris.

Needles Breaking

This is often related to needle issues:

  • Bent or damaged needle tips – Even slightly damaged needles can cause breaks. Replace promptly.
  • Wrong needle system – Use 130/705H needles. Many needle systems won’t fit properly.
  • Needles not inserted correctly – Make sure needles are fully inserted and completely upward.
  • Hitting pins or thick seams – Use care to avoid collisions that can bend needles. Remove pins.

Skipped Stitches

Stitch skipping can have multiple causes:

  • Incorrect threading – Double check all threads are seated in tension disks and passing through guides.
  • Fabric pulling – Don’t pull fabric, let machine feed it. Hold fabric taut but not stretched.
  • Wrong needles – Damaged or incorrect needles may deflect and skip stitches.
  • Presser foot pressure too low – Increase pressure so fabric moves with feed dogs and stitches don’t skip.

Poor Stitch Formation

Sloppy, uneven stitches usually indicate a tension issue:

  • Not engaged in tension disks – Lift presser foot and rethread to ensure threads are seated in tension disks.
  • Debris in tension disks – Remove and clean out disks if thread, lint or oil is present.
  • Tension too loose – If stitches are irregular, tighten thread tensions incrementally until balanced.
  • Dull or bent needles – A damaged needle tip can affect stitch formation. Replace promptly.

Fluting Seams on Knits

This wave-like distortion of seams happens when differential feed needs adjusting:

  • Differential feed too low – For knits, increase differential feed up toward max of 2.0.
  • Tension too tight – Loosen needle tension slightly to improve flexibility of knit seams.

Puckered Seams

Fabric puckering is also related to differential feed:

  • Differential feed too high – Lower differential toward 1.0 for woven fabrics susceptible to puckering.
  • Dense/heavy fabric – Puckering can occur with too much fabric in the stitch space. Reduce cutting width.
  • Tension too tight – Loosen threads if fabric is puckering. Lightly press seams to check puckering releases.

Fabric Edge Curling

Edges that curl under typically indicates the cutting width needs adjusting:

  • Cutting width too wide – Use cutting width dial to reduce width to eliminate curling.
  • Rolled hem setting engaged – Disengage built-in rolled hem if not actually doing rolled hems.

Looped Threads Too Loose

Loops of upper looper thread forming on underside of fabric means looper tension needs tightening.

  • Looper tension too loose – Slowly tighten looper tension dials until excess looper thread stops forming loops.

Helpful Resources for MO-735 Troubleshooting

In addition to this troubleshooting guide, here are some other helpful resources for diagnosing and fixing Juki 735 problems:

  • MO-735 Instruction Manual – Provides threading diagrams, tension guides, troubleshooting tips.
  • Juki Dealer Training Manual – Expanded troubleshooting explanations from company.
  • YouTube Videos – Many available showing common adjustments and fixes for 735 issues.
  • Sewing forums – Search for help from experienced users who have likely solved your problem before.
  • Sewing machine repair technician – For fixes needing specialized tools or expertise.

Preventing Future Problems

While occasional issues are bound to occur even with regular maintenance, you can help prevent many Juki 735 problems by:

  • Always using the correct needle system (130/705H).
  • Replacing needles at first sign of damage or wear.
  • Using quality thread appropriate for fabric type.
  • Cleaning lint and oils from tension disks regularly.
  • Avoiding collisions of needles with pins or thick seams.
  • Ensuring any repairs are done by authorized Juki technicians.
  • Taking machine in for periodic servicing per owner’s manual.

We hope this detailed troubleshooting guide for the Juki MO-735 helps you quickly diagnose and resolve any issues that arise so you can get back to creative sewing! Let us know in the comments if you have any other tips to share from your experience with the MO-735.

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