Bobbin is not feeding properly- didn't wind on evenly.

Your talking about the bobbin? If so your not threading it properly to feed the bobbin while winding. Sounds like you don't have the proper tension from proper threading.

I think that maybe it's not threaded properly. I have had this happen a few times and had to re thread it. I leave mine threaded all the time because it can be hard to get it done correctly.
Good Luck.

Sounds more like the way the bobbin has been wound, is it loose and uneven or tight and smooth. Is it properly into the tension spring? being loose doesn't sound right, a thread under correct bobbin tension is usually pretty firm.

Is it loaded into the bobbin holder the right way ?

Also check the bobbin itself hasn't been damaged in some way, not worn/bent. It needs to turn smoothly in the bobbin holder so if one edge has been bent a little this will cause problems.

When winding bobbins, you must have tension on the thread so it winds smoothly with consistent tension on the thread. Most machines have a little tension disc on top or the thread goes through the regular tensioner in order to achieve this. But I always wind bobbins at about 3/4 speed and also add a little extra tension by holding my scissors handle on top of the thread spool so it doesnt bounce around. Also start winding with a little tail pulled through a hole on top of the bobbin and wind until this starting end is covered, then stop and snip off the tail. Then continue winding and watch the thread, giving it a nudge so that it fills evenly across the bobbin, not just all in the middle.

Think of it like the garden hose reel; if you wind it really fast the hose all goes into the middle of the reel, then jams up and you can't get the whole hose onto it. Same thing, wind smoothly and evenly across the whole depth of the bobbin so that the thread is smooth and even. Then when the thread feeds off it will be smooth evenly tensioned and should stitch out evenly.

There is some good trouble shooting information on this page too which might help you to work out what is causing this thread breakage.
http://sewing.about.com/od/sewingmachineindex/a/mtroubleshot.htm

1. Do you mean that there are knots in the bobbin thread?
2. Is the bottom thread in your stitching looping and knotting.

If yes to 1. you need to rewind your bobbin fresh, and keep slight tension on the thread reel that you are winding it from. Put the handle of your scissors into the top of the reel to apply a gentle pressure while winding. Keep your eye on the bobbin as it winds and give it a nudge with a finger tip to ensure it winds the bobbin evenly top, middle and bottom.

If yes to 2, then you need to check your bobbin threading, is the thread even under tension. Is the bobbin tension set correctly. Break out your manual and revisit this to ensure it is set correctly.

Hello

Make sure your feeddogs are up. That is the little jagged looking plate under the pressure foot. There should be a setting on your machine that will move it up and down.

If they are up then the bobbin is not in correctly. If it is a normal round bobbin that fits in a bobbin case, hold the bobbin in front of you so that the thread end is on top and the thread is going away from you, and slide it into the bobbin case. Feed the thread through the right openings in the bobbin case. When you pull the thread end the bobbin should turn clockwise.

Never hand-wind bobbins. Instead, use the accompanying bobbin winder which is attached to most machines,bobbin casings must be oiled regularly to prevent problems with the bobbin turning properly. The bobbin, when inserted properly into the bobbin casing, should spin counter-clockwise when thread is pulled.

Check the way your machine is threaded. Completely un-thread your sewing machine and re-thread it. Remember to always thread your machine with the presser foot up.

Check the bobbin and be sure the bobbin is threaded correctly and that the bobbin case is correctly threaded. Be sure the bobbin is in the bobbin case in the correct direction.

Always watch for bobbin wear, especially on the plastic type of bobbins. If the edges of the plastic are showing abrasions, the size of the bobbin has changed and may be the culprit. Although the size change is minute, it allows the bobbin to wobble in the case and changes the tension.

Check the manual for your machine to make sure you are feeding the thread through the correct guides and connecting with the bobbin as indicated.

Iam very picky about my bobbins!

make sure you are threading the machine for the bobbin correctly, In my opinion I don't think any machine really winds well.

What I do is hold the thread about an 1" away from the bobbin. start to wind and I guide the thread slowly up and down the bobbin so that it winds even

The tension used to wind the bobbin is not wright, remove all the thread and rewind the bobbin. Make sure that you put the bobbin in place exactly as shown on the image, I didn't in the beginning and couldnt figure it out, now I now IT IS VERY IMPORTANT TO PLACE THE BOBBIN CORRECTLY.

Verify that your thread path is correct when winding the bobbin. It has a distinctive path including a tensioner that helps your thread wind smoothly. Do not use a bobbin that is not wound smoothly because (as you already know) it could possibly break needles and damage the machine.

Brother CS 80 Sewing Machine Bobbin Rewind