My Brother sewing Machine Model SB4138 Product code 885-U24 Sews but it will not pull up the bottom thread from the Bobbin. Only top thread works

Check your stitch sample. Dollars to donuts it's the top thread bird nesting (also called thread nesting) under the fabric. Issues appearing under the fabric is usually top thread related. Problems appearing on the top of the fabric is usually bobbin thread related.

Remove the top thread from your machine.
Be sure to start with a brand new needle.
ALWAYS RAISE the presser foot and rethread the top.

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go to a sewing machine repair shop ( preferably one that services your make of machine ) and talk with them as to what is happening and what you are doing

remove the thread and bobbin.
take out your manual and follow the exact instructions for threading and inserting bobbin.

If this does not help check the tension on the top(the number should be about mid way).
If it is too low it will bunch up on the bottom.

Check that the thread is tight around the bobbin. Make sure that the bobbin is in the right way around - the bobbin thread should double back on itself coming out of the bobbin holder. The bobbin tension adjustment is the small screw in the plate on the bobbin case that the thread passes under as it comes off the bobbin and goes out.

The bobbin case is not in the shuttle.

Raise the needle to it's highest position.

Lift the lever on the back of the bobbin case and hold it open as you insert the case into the shuttle; arm on the case pointing up. You may have to turn a bit to the left or right - it will click when in place.

Hi! This is the machine I use (mostly) and I've found it really doesn't like lint. I brush out lint every few hours and it has made a huge difference in how my machine sews. I suspect your machine may be as sensitive to lint as my is, so give her a really good cleaning. Then, rethread (yes, I know you've done that already, but do it again, for grins.) everything. Pay careful attention to the way the bobbin thread comes off the bobbin (from left to right) when you rethread. If you usually use the automatic bobbin pickup, don't. Pick up the bobbin thread the regular way, and, holding the top thread and bobbin thread securely in your left hand, start to sew.
I sure hope this helps!
Please let me know if this works, ok?

Robbie

The tension in the top thread is controlled by a dial, and the tension in the bottom thread is controlled by a small screw on a spring on the bobbin. The tensions are supposed to be exactly equal in order to make the stitch perfectly in the middle of the cloth. Uneven tension will pull the stitch up or down from there. You can tug on each thread to feel how much tension there is. Often the bottom will get too much tension by just inserting the bobbin upside down. Leave the bobbin door open, and watch the operation. The top thread is pulled down around the bobbin. See if it is getting caught on anything?

I would take it to a mechanic.

You can find a Users Manual plus a workbook that you can get in PDF and print. Users Manual is 44 pages and workbook is 58 pages. Go to www.mannualowl.com and search for Singer CG 590n manual. It's all free.

The top of the machine is not threaded correctly. First raise the presserfot then rethread the machine. Bottom looping is usually caused by a lack of top tension. There could allso be a bur on the hook.