My ls2125i won't stitch

Top thread is "frayed"?

Could be tension is too high, problem with needle, needle wrong type, other.

Does it straight stitch ok using same fabric, thread, needle, bobbin, and tesnsion?

you probably wont find it listed anywhere as it is from experience and changes with different material thickness and needle size
SO how to set tension
thread the machine and adjust the tension until you feel a drag on the thread
now thread the needle and sew a piece of scrap material
if the thread bunches up underneath then increase the thread tension until it sews properly
if the bottom thread is pulled to the top or the thread keeps breaking loosen ti off a bit
when the stitch is being properly formed , both bottom and top threads should meet at the center of the two materials being sewn

was the presser foot lowered? check if the loop-taker is properly installed or seated.

lower your needle. If up to high can't catch the bobbin thread.

I think you are saying no stitch is formed also referred to as the needle not catching thread. Below offers a variety of diagnoses and solutions which are straight forward.

Sewing Machine Needle Not Catching Thread

Below is general advice quoted from 6 common sewing machine problems solved:

Skipped stitches are usually due to a bad needle. The needle may have become damaged or bent by sewing material too thick for the needle, forcing material through the feed dog, or hitting a straight pin. If the problem seems to be consistently reoccurring, it may be due to forcing the fabric. Sewers should allow the feed dog to pull the fabric and only use their hands to guide the fabric through the feed. When sewing knitted fabrics, using a stretch needle can help prevent skipped stitches.

Below is a video showing how thread is hooked into a fabric:

Sewing Machine Anatomy How Stitch is Made

try changing the needles---are the needles the correct size for
the fabric being sewed?
make sure you have long thread tails--that what I do on my
serger
you can try to post the picture

Hello,
Here are a few things to try.

* Raise your feed dogs if your machine has this feature.

* When you start to sew a seam, hold the upper and bobbin thread tails. Hold them back and out of the way as you sew your first couple of stitches. This will keep them from getting caught in your machine.

* Your fabric may require a different needle. Generally, heavier fabrics require larger needles and thinner fabrics, smaller needles. You may also need a larger needle if you're sewing through many layers of fabric. And make sure to use a ballpoint needle for knit fabrics and a sharp needle for woven (or a universal needle for either). And make sure your needle is appropriate for the type of thread you're using.

* Adjust the pressure of your pressure foot, it may be too light for your fabric.

* If your upper thread and bobbin threads are different types, try using the same thread for both. And use a good quality, brand name thread.

* Change your needle plate. Try switching to a needle plate with a smaller hole (a straight stitch needle plate).

Important Note: If you change your needle plate, check to make sure your needle aligns perfectly with this smaller hole before starting to sew. A misaligned needle could hit the plate and break, which could be dangerous. And make sure to change your needle plate back for zigzag and other wide stitches.

I hope this helps.

Hello,
Here are a few things to try.

* Raise your feed dogs if your machine has this feature.

* When you start to sew a seam, hold the upper and bobbin thread tails. Hold them back and out of the way as you sew your first couple of stitches. This will keep them from getting caught in your machine.



* Your fabric may require a different needle. Generally, heavier fabrics require larger needles and thinner fabrics, smaller needles. You may also need a larger needle if you’re sewing through many layers of fabric. And make sure to use a ballpoint needle for knit fabrics and a sharp needle for woven (or a universal needle for either). And make sure your needle is appropriate for the type of thread you’re using.


* Adjust the pressure of your pressure foot, it may be too light for your fabric.


* If your upper thread and bobbin threads are different types, try using the same thread for both. And use a good quality, brand name thread.



* Change your needle plate. Try switching to a needle plate with a smaller hole (a straight stitch needle plate).


Important Note: If you change your needle plate, check to make sure your needle aligns perfectly with this smaller hole before starting to sew. A misaligned needle could hit the plate and break, which could be dangerous. And make sure to change your needle plate back for zigzag and other wide stitches.

Hope this helps.

Hello,
Try these solutions.

* Re-thread your needle
It may be threaded incorrectly (backwards).

* Reinsert your needle
Make sure it goes all the way into the holder and that it’s positioned correctly – usually with the
flat side away from the bobbin, but consult your machine’s manual to be sure.

*Change your needle
Your needle may be blunt, bent, or otherwise damaged.

*Your fabric may require a different needle. Generally, heavier fabrics require larger needles and
thinner fabrics, smaller needles. You may also need a larger needle if
you’re sewing through many layers of fabric. And make sure to use a ballpoint needle for knit fabrics and a sharp needle for wovens (or a universal needle for either).
And make sure your needle is appropriate for the type of thread you’re using.

* Adjust the pressure of your pressure foot
It may be too light for your fabric.

* Change your thread
If your upper thread and bobbin threads are different types, try using the same thread for
both. And use a good quality, brand name thread.

* Adjust your thread tension
It may be too tight or too loose.

* Re-thread your machine
It may be threaded incorrectly.

* Change your needle plate
Try switching to a needle plate with a smaller hole (a straight stitch needle plate).

Important: If you change your needle plate, check to make sure your needle aligns perfectly with
this smaller hole before starting to sew. A misaligned needle could hit the plate and break, which
could be dangerous. And make sure to change your needle plate back for zigzag and other wide
stitches.
I hope this helps you.

birdsnest refers to a mess of thread on the underside of fabric when you start sewing (after a few stitches all looks good). if this is the case and it is happening during embroidery, switch off jump stitch thread cutting.

if it happens at the start of normal sewing, either hold your needle thread when you start sewing or make sure the needle thread is under the presser foot and held by the presser foot when you start sewing. this way you will have an inch or so of thread on top of your fabric which you can trim instead of a mess underneath.

if there is a mess underneath for more than first few stitches, either your check spring in the needle tension area is set incorrectly, or your needle tension is set too loose (adjustable in sevice menu by tech only) or there is foreign matter caught in tension assembly preventing proper tension.

scott