Bobbin thread is bunched up when sewing straight stitch

Skipping stitches and thread breaks
Skipping stitches and thread breaks

Sewing Machine Thread Bunching Up? Here's Why!
Sewing Machine Thread Bunching Up Here Why

PDF]INSTRUCTION MANUAL - Janome

janome.com/siteassets/support/manuals/.../inst-book-7318-english.pdf
making any other adjustments mentioned in this owner's manual. ..... 16 q w e r t. SECTION 3. BASIC SEWING. Straight Stitch Sewing. Machine setting: q Stitch ...

How to Thread a Janome Sewing Machine - YouTube

? 6:55
https://www.youtube.com/watch?v=NUsT0plWt6Y
Mar 1, 2013 - Uploaded by Easy Sewing for Beginners
In this video I show you how to thread a Janome sewing machine ... I've unwrapped it and started reading the manual and it wasn't easy to see ...

aside from cleaning, with a thread bunching problem it's always good to change the needle and make sure the top thread has not come off the thread take up lever and make sure the bobbin is turned the correct way in the bobbin case.
as for the zig zag stitches, it sounds like a gear or cam could be damaged or worn.
if someone brought me a sewing machine with the same problem, the first thing I would check for is a damaged or worn gear..

try changing the needle--use a needle according to the fabric
being sewed
if thin fabric is being sewed try using a stablizer
rethread the machine top and bobbin--use every thread guide
make sure the bobbin is inserted correctly and turned correctly
in the bobbin case
also try adjusting the top thread tension just a little

Try these suggestions
1. Change needle
2. Rethread the machine--top --make sure to use every thread guide
3. Take the bobbin out --make sure it is inserted correctly into the bobbin
Case, & make sure the bobbin is turned the correct way
4. make sure the thread has not come off the thread take up lever
5. Clean under the needle plate & in the bobbin area for lint or threads

try rethreading the machine top & bobbin
check to see if the thread has come off the thread take up lever
try changing the needle
also make sure the needle & thread & fabric are compatable

Recheck your bobbin and make sure it's in the bobbin case correctly.There may be arrow diagram on face plate or bobbin case. You can also check owner's manual to make sure bobbin is inserted the right way. If it isn't, the bobbin thread can "whiplash" causing the bunching you've describe. If you have smooth stitches on top, your top threading is all right. I hope this helps. If it does, please let Fixya know by rating my solution.

re thread the top and bobbin threads

after pulling up the bobbin thread pull both threads to the back and hol them when stitching the first few stitches

with out holing the threads the machine will pull the thread into the machine and bunch the thread

Remove the needle plate and clean the feed dogs there could be fluff gathering.
Check your needle is not damaged.

Try these time savers:
Test your thread quality to start, thread your machine and LIFT the presser foot (this opens the tension disks). Pull your top thread straight back. If you feel no tension no mater how much thread you pull, your thread is good. If that your machine passes that test, then let me know, we can go to step 2. If not, try different spool of thread, same test until you get a smooth pull (tip: always check your thread this way when you thread your machine)
Step 2:
Pull on your threaded bobbin thread while it’s in the machine. Does it pull smooth and even? If so, go to step 3. If not, try a new bobbin (bobbins get bent or distorted if wound too tight).
Clean thoroughly in the hook and bobbin case area and oil 1-2 drop is all.