My Necchi Sofia 300. When winding bobbin the needle doesn't disengage and the matching makes a dreadful grinding noise as it winds the bobbin

If the needle on your Singer Quilter Confidence machine moves when you're winding the bobbin, it's likely due to a few possible reasons. Here are some steps you can take to resolve this issue:

1. Check the threading: Make sure the thread is properly threaded through the machine, as an incorrect threading can cause the needle to move during bobbin winding.
2. Tighten the needle clamp screw: If the needle clamp screw is loose, it can cause the needle to vibrate during bobbin winding. To tighten the screw, use a screwdriver to turn the screw clockwise.
3. Check the bobbin winder tension: If the bobbin winder tension is too loose, it can cause the needle to move. To adjust the tension, refer to the manual for your Singer Quilter Confidence machine.
4. Check for any obstructions: Make sure there are no obstructions near the needle, such as thread tails, fabric, or lint, as these can cause the needle to move during bobbin winding.

If you've tried all of these steps and the needle continues to move during bobbin winding, it may be a mechanical issue that requires a professional to fix. I would recommend contacting Singer for further assistance.

The issue you are describing with your Singer 9960 bobbin winder could be caused by a few different things. One possibility is that the clutch is not properly engaging or disengaging. Another possibility is that the bobbin winder belt may be loose or damaged, causing the needle to move up and down and making noise while winding the bobbin. It is also possible that there may be a problem with the bobbin winder mechanism itself.
I would recommend checking to make sure the clutch is engaging and disengaging properly, and check the bobbin winder belt and mechanism for any signs of damage or wear. If you continue to experience problems, it may be best to consult the manual or contact the manufacturer for further assistance.

Sounds like a fancy new machine. I am not directly familiar with that machine, but I am very familiar with the same problem in Vintage mechanical machines, and perhaps most of it will have a counterpart to resolve your problem. 1. The first thing to check is the mechanism used to Lock and Unlock the Machine drive train when a Bobbin is being wound. (A) On much older machines, this is usually a knob located in the middle of the Handwheel, Turn one way to engage the power train, and turn the other way to disengage the power train. (B) On slightly older machines this is located in the same place (center of Hwndwheel), but is a Push-Toggle mechanism, push one part in and it disengages the Drive Train, used when winding Bobbins, push it back to Normal to re-engage the Drive Train, so the needle goes up and down again. (C) Your machine may be similar to one of these, or if it is far more electronic, then there is a special Switch or Setting to do the same thing. Check your Owner's Manual to see how your machine engages and dis-engages the Drive Train that makes the needle go Up-And-Down when you sew, or not go Up-And-Down when you are winding a Bobbin. Since this Bobbin winding option involves disengaging the Drive-Train, if it gets damaged or worn out, it disables your machine. For this reason, I do not recommend home sewing machine operators to eve use the Dis-Engage feature when they are winding Bobbins, just be sure the Presser-Foot is in the UP position. The Needle going Up-And-Down won't damage anything for that short while. 2. Another area to check is the Bobbin Winding mechanizim. Be sure it is disengaged so ther is no drag on the machine. On the newer machines, maybe even yours, the two mechanizims to Start and Stop the Drive-Train and the mechanizim to re-wind a Bobbin are inter-connected, meaning one may trip or un-trip the other. If this is the case, then all you would have to do is dis-engage the Bobbin Winder, and . . . PRESTO ! . . . your problem is fixed. Hope this Helps you fix your machine that runs but does not Drive the Needle. Sincerely, Amender, 2020-DEC-03#

if your machine has a clutch in the center of the turn wheel you must loosen it to disengage the needle before winding the bobbin. Remember to re-tighten it after winding.

Is the bobbin pushed over to engage the stop

Under the lid you will find the bobbin winding stem and the mechanism that is meant to "flick" home when the bobbin is full. This mechanism may be sticking. It may need a small amount of lubrication.
It may need tweaking with small pliers to make it work as the bobbin stem often gets knocked off line when moving the machine and this stops the mechanism from working smoothly.

This is covered in the user manual. If you haven't got one search online for "user manual + your make & model". You should get several decent hits like. http://homeappliance.manualsonline.com/manuals/device/sewing_machine

To disengage the needle while winding a bobbin do the following: the handwheel on the right end of the machine has an inner knob. hold the outer rim of the handwheel stationary as you rotate the inner knob counterclockwise. Also make sure the bobbin winding peg is pushed over to the right and the bobbin is seated on the peg.

slide the bobbin winding spindle. if that doesn't disengage the needle... your machine may need professional servicing.

there should be a way to disengage the bobbin winder. I had a machine that had a switch in the center of the handwheel and even though it would be in the off position I still had to turn the handwheel till it clicked.