CS6000i jamming bobbin case

try these suggestions
change the needle
make sure the thread doesn't come off the thread take up lever--this
can jam the machine
make sure the bobbin is turned the right way in the bobbin case--this
can cause problems if the bobbin is turned the wrong way
make sure the bobbin is not warped or damaged
make sure there are no burrs in the bobbin area or on the needle
plate

try adjusting the top thread tension-one number or letter less, then
sew on a piece of the scrap fabric if you have any. to see if that helps
try changing the needle
make sure the bobbin is turned the right way in the bobbin case, I
know this may sound crazy but it can hinder the sewing, I was sewing
a skirt the other night & I turned the bobbin the wrong way & inserted
the bobbin into the bobbin case & it didn't work good,, I took the bobbin
out of the bobbin case & had multiple threads. so I had to clean the mess up & turn the bobbin the opposite way & the machine worked
just fine

you need to have the machine checked to see if the hook & hook race
may need to be replaced & the machine may need also to be timed
a repair shop can tell you for sure

when you sew keep a eye on the thread take up lever & see if the thread comes off while your sewing, I've had this happen to me & I've been sewing for over 30 years. if this does happen, take a pair of pliers & very gently close the take up lever just alittle but not enough to damage it.
also check the needle to see if it's damaged--if your not sure change the needle--flat side goes to the back of the machine
always make sure the fabric & needle & thread are compatable--the thread must be able to pull thru the needle with out any problem
also check to make sure there are not any burrs on the needle plate or bobbin or bobbin case

here are my suggestions
1. when your sewing check to see if the thread is coming off the thead take up lever,, I've had this to happen to me & it can jam a sewing machine up
2. it's possible that the bobbin case is worn & needs to be replaced
3.also check your top tension
4. try rethreading the machine top thread & bobbin

the tread gets stuck on in the thread take up arm, there is a joint ware the arm is rived to gather, the thread get caught between arm and the rived sheet steel . . take little silicon gasket and fill in the joint so thr thread can't get stuck where its rived

That sounds like a horizontal bobbin case held in by a magnet like the Janomes have now: if so, then yes, I understand your frustration as I've replaced it on my Janome 1600P twice, always when I try to push the machine with sewing denim hems, it just won't hack it, the case will dislodge, then the needle strikes it and it jams up, again and again and again. However, my machine was serviced last year and the mechanic fitted a longer finger that holds the case down and it did fix the problem. So have you spoken to a Bernina dealer and voiced your dissatisfaction with it? Maybe they need to look at an after market fix too.

Otherwise, only other option is really to change the machine; I now use my trustly old Singer 20U when I need to seam heavy thicknesses as it can handle the heavier weight fabric okay.

Check and double check your needle for proper placement and start with a brand new one that you are sure is the right one for the machine.

Put the tension back up to about 5. Rethread the machine entirely, and make sure you have the pressure foot in the up position when you rethread. If your getting bunching on the bottom, it's probably your top thread that's bunching up. After you rethread, put a small piece of fabric under the pressure foot, lower the pressure foot, and turn the handwheel in the forward direction and watch the thread as it comes around the bobbin case. If it goes around smoothly, try it with the foot control. If it hangs up as it goes around the bobbin case, you might have a burr on the black plastic bobbin case. Take it out, check for any burrs, sand them down, and try again.

check you tension on the top thread and see if you have it threaded the right way. Also see if the indent of your needle "the indent down by the hole on the needle" is facing the hook by your bobbin case that grabs the thread when it comes around.
Greg