HOW DO YOU CHANGE FROM ONE COLOUR BOBBIN TO THE PREFILLED NEXT COLOUR BOBBIN

Check for lint/dust/thread scraps in the bobbin case. Is the bobbin locking in when you put it in the case?
Make sure bobbin is threaded properly.
Check needle and needle plate for any burrs.
Check top thread for proper threading.
Also, thread quality is important. If it's old, throw it out. A good way to preserve your thread is to put it in the freezer in a ziplock bag. Maybe one of these suggestions may help.

Try these suggestions
1. Change the needle--use a needle that's for the fabric being sewed
2. Rethread the machine--top --make sure to use every thread guide
3. try a different bobbin--make sure bobbin is inserted correctly into the bobbin case, & make sure the bobbin is turned the correct way in the bobbin case
4. make sure the thread has not come off the thread take up lever
5. Clean under the needle plate & in the bobbin area for lint or threads

you may have the fabric not tight enough in the hoop or try using the same colour thread in the bobbin

you should not have to adjust any thing one colour in bobbin the other in the machine if one thread is to thick for the bobbin then you will have to adjust the tension in the bobbin

Fist of all you should choose correct case size selected one bobbin. Then you should choose the fabric colour tone to tone or contrast colour cotton thread .And then finally you should Please see the link :
http://www.wikihow.com/Wind-a-Bobbin .

First chose the colour tone to tone or fabric colour thread new thread. Then take a bobbin left hand some 3 or 5 wring bobbin thread for right hand wring opposite side then turn the bobbin take on one big needle or screw driver near the wheel and fill the bobbin.

Check that you have got the thread correctly routed on the bobbin case and that there is noticeable 'drag' on the thread when you pull the thread out of the bobbin, in its case. If there's little or no drag, it is likely that the bobbin tension needs increasing. I'm assuming you've set the top tension to thered line. A good check is to load two colours of the same thread type top-and-bottom - when sewing on wide zig-zag, the top thread colour should be the only one seen on the top of the material and the bottom colour should be mostly seen on the bottom ... it's OK to have just a spot of the top colour showing on the underside on wide zig-zag/satin stitch.

Hi, most likely your bobbin sensor is being blocked by something. Common causes are a dirty sensor. Q-tip on the eye of the sensor inside the bobbin door. Or there is fuzz blocking it. Next take out the bobbincase and the bobbin. Look in the bobbincase and you will see a round spring. This spring acts like a brake for the bobbin. Sometimes these springs will get moved and out of position blocking the little space that the bobbin sensor reads through. Reposition the spring so you can see through it and the bobbincase.
That should do it.
Good luck.
Rick Engel
Bernina tech

It's okay - it's supposed to do that! The Needle Down button has a different function when you are in Embroidery mode i.e. you have the emb. unit attached.
It moves the emb. arm forward for two reasons: so you can cut top-side jump stitches more easily between colour changes (you touch the button again and the emb. arm returns to under the needle so you can finish the design); and secondly so you can "park" the embroidery unit when you are finished. You can then turn the machine off, remove the emb. unit and replace it in the carry case. If you DON'T do this, the emb. arm is not in the right position to fit into the moulded carry case properly.

The Broken Thread message usually means that it has started the colour, but the thread has been pulled down underneath instead of making nice locked stitches. Hold onto the thread end until the machine has stopped and beeped for you to cut the thread. This usually solves that problem. Sometimes the thread gets pulled out of your hand so just back up the stitches a few and start over, holding the thread more tightly. Don't tug on the thread - just keep a firm grip.

Designer 1s often cut the bobbin thread too short so that it can't make those nice locked stitches when it starts. You need to take off the hoop, open up the bobbin cover and use your stylus, the tip of a pair of scissors, tweezers (whatever is to hand) to pull the bobbin thread out a little. Instead of cutting it on the bobbin thread cutter, just let it hang outside by 1/8" or so. That way you can be sure there is enough bobbin thread available for the stitch to lock. Don't use the scissors button on the machine after every colour change. Sure, it makes for a tidier back of the embroidery with less work for you afterwards, but if it means you are taking the hoop and bobbin cover off after every colour change then it is not worth it in time-saving.
If your machine is doing this - cutting the bobbin thread too short - mention it to your tech. when you machine goes in for its next service. He may be able to tweak the bobbin cutter so it does not cut so close.

It not a nut its a push fit all you have to do is give a pull and the plactic retaining stud will come off with the thread bobbin so you can replace it with another colour

LOL