Right needle broke twice

The slightly rounded point of a universal needle is sharp enough to pierce woven cotton fabrics, but not so sharp it will damage knits. It comes in sizes ranging from 60/8 to 120/19-but a reasonable starting point is the 80/12 size.Aug. 28, 2017

Four Common Machine Needle and Thread Combinations

What Size Machine Needle? - Made to Sew

https://madetosew.com > what-size-sewing-machine-nee...
90/14 - suitable for medium weight fabrics, e.g. slightly heavier weight cotton, polyester, linen, lightweight upholstery fabric. Light Weight Fabrics Lighter ...

Tips for Selecting the Correct Needle Type and Size for Your ...

https://weallsew.com > tips-for-selecting-the-correct-nee...
Nov. 17, 2014 - Tips for sewing machine needle selection based on fabric, thread, ... Small needles sizes - 60/8, 70/10, 75/11 - are best used with fine ...

What Size Sewing Machine Needle For Cotton

https://sewingmachinebuffs.com > what-size-sewing-ma...
6 days ago - The best needles for cotton fabric are medium-sized needles like 80/12, 90/14. They work well with quilting pieces of cotton, lightweight ...

Needles Guide

https://www.jjneedles.com > needles-guide
Choosing the right sewing needle. ... Below is some information for you, it covers common needle sizes and use, it contains clickable links which will take ...

Have you tried removing the needle and putting it back on to make sure it is seated correctly and tightly?

Machine breaks needles
1.make sure you are using the right needle for your type of sewing machine.
. There are cases where the machine will only use ones specified in the owners manual.
2.the presser foot may not be installed properly
3.use the correct needle for the type of fabric you are working with. To fine of needle on heavy fabric or to course a needle on silk or jersey can damage fabric.
4.let the feed dogs guide the fabric & the feed dogs will work with the presser foot .
5.the needle is not all the way in -push all the way up against the stop
6. Check top thread tension
7. machine could be out of time & need to be serviced

For the cover stitch, only use a size 90 needle. Depending on the type of knit, use a ball point or stretch needle. The 936 uses standard sewing machine needles, so you can switch needles with the type of fabric, just like with a sewing machine.

It sounds like you may be using the wrong needle. For knit fabric you need a ball point needle in order for it to sew correctly. A regular sharp type needle can cause the stitches to skip. Also make sure you have the right size for the type of fabric. Lighter weight fabric needs smaller size needle and thicker types need bigger sized needles.

Also make sure you have the right presser foot and the right pressure on the presser foot to get nice even stitches. A roller foot helps when sewing knit fabrics.

I also own 2 necchi sewing machines, my mechanical is a 4595,,
lower thread tension
to test the bobbin tension, remove the bobbin case & bobbin & hold it by suspending it byb the thread, **** it once or twice, if the tension is correct, the thread will unwind by about an inch or two.
if the tension is too tight, it does not unwind at all, if the tension is too loose, it will drop too much.
to adjust the tension,, left is loosen & to the right tighten

thread breaks
rethread the machine making sure to get all thread guides
top thread tension usually 3 or 4
replace needle- make sure the needle is inserted correctly
some needles don't work with some thread, here's a tip

Cut 6-8 inch piece of thread of the spool you are going to use for your project
Take the needle you are going to use for the project
& insert the thread thru the eye of the needle
& lift one end of the thread to a 45 degree angle
& if the needle is the right size for the thread it will slide down the thread
But if the needle hangs on the thread you need one size larger needle for the thread

here are something you might check
upper thread breaks
1.top tension to tight
2.thread to thick or to fine for needle
3.needle not inserted correctly
4.thread caught on something-spool pin, tension area
5.needle damaged
6.needle thread is not threaded properly

Needle breaks
wrong size needle for fabric
wrong foot is attached
needle clamp screw is loose

also check for lint & pieces of broke needle under the needle plate
also the bobbin case area -take the bobbin & case out & check for pieces of broke needle

here is a tip about needle & thread
Cut 6-8 inch piece of thread of the spool you are going to use for your project
Take the needle you are going to use for the project
& insert the thread thru the eye of the needle
& lift one end of the thread to a 45 degree angle
& if the needle is the right size for the thread it will slide down the thread
But if the needle hangs on the thread you need one size larger needle for the thread

Make sure the needle is in correctly. On most machines the flat part goes towards the back of the machine. Also make sure you are using the correct size needle for the type of thread and fabric you are using. Thicker fabrics such as denim and upholstery fabrics will require a thicker needle, like a 100 (16).

Are you sure that you have but the bobin in right? If it is brand new you can take it back to the dealer and he won't charge you

Probably just the needle. Try turning it 180 degrees