Bobin not rotating freely - Husqvarna Scandinavia 100 Sewing Machine

I'd call it a bobbin drive gear, but your best bet is to look for a parts list for your machine. These usually have diagrams and tables that give the manufacturer's part numbers.

You probably knocked it out of time. There are two push buttons on the base of the machine. One of them is for resetting the timing. Press the button down and rotate the hand wheel until the button (locks-in) to a groove continue to rotate hand wheel until you hear a click. That click is the clutch re engaging, after doing this you should be able to sew just fine.

Chris
glfi.com

There is a way to adjust this though it is quite labor intensive and takes some specialized tools. My first recommendation would be to change the needle. The timing on BERNINA machines is far less likely to be off than on most other modern machines. The chances are far greater that your needle may be bent and is hitting the hook.

Your timing is probably the problem and will need to be adjusted by a repair shop. Sadly, it requires special tools and expertise.

From your description it appears that you have tried tension settings on the upper tension control adjustment knob without success.
Check that the bobin tension is adjusted correctly by taking out the bobin complete with the spool.
Pull the cotton thread and it should be a smooth light pressure if the tension is correct. If it is tight to pull or pulls freely then adjust the tension screw which is found on the outside of the bobbin. The screw is very small and requires a minature size screwdriver. The adjustment will only be a slight turn of the screw one way or the other to obtain the correct tension(depending if it was loose or tight).
Once this is set reinstall the bobin and tread up the machine, hopefully with the upper tension set at approx."2" the machine will sew correctly.

Try changing your needle.

This is an answer to another person with a similar complaint. Try the suggestion below, it may fix the problem.

From your description it appears that you have tried tension settings on the upper tension control adjustment knob without success.
Check that the bobin tension is adjusted correctly by taking out the bobin complete with the spool.
Pull the cotton thread and it should be a smooth light pressure if the tension is correct. If it is tight to pull or pulls freely then adjust the tension screw which is found on the outside of the bobbin. The screw is very small and requires a minature size screwdriver. The adjustment will only be a slight turn of the screw one way or the other to obtain the correct tension(depending if it was loose or tight).
Once this is set reinstall the bobin and tread up the machine, hopefully with the upper tension set at approx."2" the machine will sew correctly.

Try taking the covers off again. Now check under and around the bobin case, thats the black plastic bit that holds the bobin. Look for any fuzz or stray bits of thread inside the machine and and around the feed dogs and under the needle too. I use compressed canned air to get in and really blow everything clean. For some reason if the machine is not totally clean, inside the bobin gets tangled up. If you have had even one knot, odds are parts of it are still floating around inside there somewhere and stopping some little lever from moving and jamming your whole machine. Clean under the bobin case too since lint can left it up and keep the bobin from being perfectly level. Also inspect your bobbin case to make sure it isn't scratched along the edge that rotates back and forth. Even a a tiny scratch will cause it jump its tracks and your bobin will lift up and become jamed. In that case you just have to buy a new bobin case. But most of the time your culprit will be some stray bits of thread or lint.

i think your putting in your bobin backwards,
to check put your bobin in and hold bobin , and bobin case by thread if it unrolls its backwards,
hope this helps!!

I have the same problem, I fix it by removing both Shuttle hook and Bobbin Case and tested it to see if the shuttle hook rotated freely within bobbin case. I noticed the screw for the tension spring was too high and was rubbing agaist bobbin case. Just tighten screw on spring and and recheck for rubbing.