Need new bobbin case

It is probably one of two things,
1st..always put the needle plate on before you install the bobbin case. You can lock the bobbin case down by putting the needle plate on after putting the bobbin case in. Take off the plate and remove the bobbin case, install the needle plate, then install the bobbin case.
2nd...your bobbin case may be damaged now, if it is scratatched or chipped get a new case.

Good Luck

Is there is a wad of thread that is holding the bobbin captive? If so, you'll need to use small scissors and tweezers to snip away and pull out the threads. Patience!

If the bobbin is actually stuck in the bobbin case, it could be because it is the incorrect bobbin for the machine or the bobbin was over-filled with thread. You may just need to use force to remove the bobbin. It may damage the bobbin and, possibly, the bobbin case. They are both replaceable. Or you can pick up an additional bobbin case and bobbin and try the new ones in your machine.

try a new bobbin
make sure it's inserted correctly into the bobbin case
make sure the bobbin is turned counter clock wise in the bobbin case
could also be a problem with the computer, may need to be checked

I would check out Ebay for this

Are you lifting the little lever on the side and holding the bobbin case by it when you put the bobbin case into the machine, and then tapping the lever flat to the bobbin case once it's in? That should do it. If it doesn't, you may need a new case or the spindle everything fits onto may be damaged.

Hello Lisa, There is a lever on the bobbin case that is spring loaded that secures the bobbin case to the shuttle or rotary hook, whichever you have. If you have the bobbin case in the correct position and the bobbin case pushes completely onto the stem of the shuttle but does not latch onto the stem to hold it in place, you may need a new bobbin case.

Standard type bobbin case that can be bought on ebay or any sewing machine shop

It could be that the needle is hitting a point on the bobbin case causing the rough area.
Try inserting a new needle making sure it is as far in as it will go.
You could google for spare parts for your edition and brand of machine and get a new bobbing case, not expensive.
Otherwise it could be timing, which a professional would need to adjust.

try taking out the bobbin and turning it around if that dosen't fix it then you need a new bobbin case

Go for it! Just sew very slowly at first, maybe just turn the handwheel by hand to make sure you don't toast the new bobbin case. If the new bobbin case doesn't fix the problem then you will need to take it in for service, it may need adjustments that most people dont' know how to do.
good luck!