Trying to sew straight stitch but stitch loose and lots of thread on bottom

Is your bobbin threaded correctly? You should be able to pull out the thread slowly while feeling it very slightly holding back. It should not pull out easily or quickly.
Could be something wrong with your tensions, try adjusting the upper tension first by starting at the middle setting and working gradually higher and then lower till you get a neat even stitch.

If the bobbin thread is pulling through to the top of your fabric, your needle thread tension is too tight. Loosen the top tension until the needle and bobbin threads meet in the middle of the fabric.

According to the manual, you should not need to adjust the bobbin tension (and I located other sites which stated the bobbin tension cannot be adjusted on this machine). Apparently, all the tension adjustment is accomplished through the upper thread::
"EN Thread Tension Upper thread tension Basic thread tension setting: "4". (1) To increase the tension, turn the dial to the next number up. To reduce the tension, turn the dial to the next number down. A. Normal thread tension for straight stitch sewing. B. Thread tension too loose for straight stitch sewing. Turn dial to higher number. C. Thread tension too tight for straight stitch sewing. Turn dial to lower number. D. Normal thread tension for zig zag and decorative sewing. Correct thread tension is when a small amount of the upper thread appears on the bottom side of fabric. Lower thread tension The bobbin tension has been set correctly at the factory, so you do not need to adjust it. Please note: - Proper tension setting is important for strong seams. - There is no single tension setting appropriate for all stitch functions, thread or fabric. - A balanced tension (identical stitches both top and bottom) is usually only desirable for straight stitch construction sewing. - 90% of all sewing will be between "3" and "5". - For zig zag and decorative sewing stitch functions, thread tension should generally be less than for straight stitch sewing. - For all decorative sewing you will always obtain a nicer stitch and less fabric puckering when the upper thread appears on the bottom side of your fabric. 1 A B C 22 D"

Doing further research, I found this statement on a machine review site:
"After reading reviews online from where I've bought my drop-in bobbin machines, I think many of the negative reviews are due to the bobbin thread coming up without laying across the bobbin. It can cause the stitches to look very sloppy and no amount of tension adjusting can fix the stitches."

There are several machine review sites wherein 4423 owners stated their disappointment in the 4423's performance. Some said the machine failed almost immediately and others said the machines developed problems when sewing heavy fabric.

You bobbin tension CAN be adjusted. First, thread your machine with different colors in the top and bobbin, set your top tension at its default, and run a line of straight, and then a line of zigzag stitches, and compare the results at the top and bottom. You will be adjusting your bobbin to your top tension. If the top tension looks like a straight line instead of stitching and the zigzag looks like "chicken tracks" instead of a zigzag, but the bottom looks like a zigzag, your bobbin tension is too loose.

Remove the bobbin case, and locate the straight-slot screw. There are generally two; one is a Phillips and one is straight--you want the straight one. Leave the other alone.

The rule is "lefty-loosy, righty-tighty." If your stitching displays the above symptoms, it needs to be tightened, so turn 1/4 turn to the right--no more--then test again. You will need patience, but don't turn more than that. It is easy to do, but if you don't do it systematically, you can make things worse, and very slight adjustments can alter the stitching significantly.

Start from the begining.
Use your Instruction Book and make sure the machine is threaded correctly.
Put in a new needle.
Adjust the top tension to about halfway.
Fit a fresh wound bobbin that does not have all sorts of different threads still wound on it(a bad habit with a lot of people).
Make sure the bottom tension is correct.
Make sure the bobbin is fitted corectly.
Set the machine to do basic straight stitch(mid range stitch length).
Try sewing and see if the problem is solved.

it's very possible that the machine is slightly out of time & needs to be service at a sewing machine shop
is the fabric & thread & needle compatable with each other?
did you use every thread guide when threading the machine?
is the bobbin in correctly?
is the bobbin warped?

Hello

Adjust the tension

Load your sewing machine with one color on top, threaded through the needle. Load the second color thread into the bobbin and thread.


Fold the scrap fabric in half, and sew a straight stitch at least 2 inches long. Look closely at the seam. If you see loops of the bottom color thread on top of the fabric, proceed to Step 3. If you see loops of the top color thread on the bottom of the fabric, proceed to step 4.


Loosen the top tension. Since the top tension is so tight, it is pulling the bottom thread up through the fabric. Loosen the top tension by turning the numbered knob on the front of the sewing machine counterclockwise by one number.


Tighten the top tension. Since the top tension is too loose, the bottom thread is pulling the top thread down through the fabric. Tighten the top tension by turning the numbered knob on the front of the sewing machine clockwise by one number.


Sew a straight stitch 3 inches in length. Check the stitching. It is perfect if the threads meet in the middle, and you can only see the top thread on top and the bottom thread on bottom. If it still needs adjusting, go back to step 2 to repeat the needed steps.


Using two different colored threads makes it easier for you to see which thread is being pulled.

Always use proper precautions when working with electrical machines.

Make sure first of all that you have a perfect needle in and the correct way round, failing that you may need to retime the machine, if you email me I will attach instructions.
[email protected]

You can try adjusting your stitch length this may solve the problem right away.
It could be the thread your using, I have had to switch threads before. Rewind your bobin, sometimes issues can occur by a poorly wound bobin.
You can also try to use a different foot (my machine comes with a satin stitch foot)and or slow the speed of your feed dog.
Sometimes a very fabric does need some sort of backing, a tear away, or wash away might be your only answer.
I hope this helped.

Could be a tension issue.

Try this to see if it helps:
Remove top thread.
ALWAYS RAISE the presser foot and rethread from the beginning.
Start the top tension set at the midway point and then adjust.
Check that the bobbin is threaded and installed correctly.

Understanding Thread Tension Threads

Sewing Lesson 10 How to Fix Tension on Your Sewing Machine