My elna 2800 is jamming the bobbin the thread keeps wrapping around the bobbin case. What can I do

The only thread that should be under the bed of the machine should be on the bobbin itself and the thread tail that extends beyond the bobbin. If thread is wrapped somewhere else, that needs to be eliminated and the machine cleaned of all debris.

check for lint and cotton wrapped around the bobbin shaft and jamming against the housing

Sometimes it helps to try to remove the needle and the bobbincase. If you can get the bobbincase loose, the thread nest can then be removed.

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Probably unevenly wound on the bobbin. Or tension needing adjusting, be careful to note where tension spring started before adjusting and do in very small increments.
Perhaps the spring has some fluff stuck on it and thread cannot slide through easily. Take out bobbin and clean

Try taking the bobbin case out and re-insert. It sounds like the case that holds the bobbin is not inserted correctly. You might also try checking to be sure that the needle is inserted properly. Sometimes the needle gets loose and drops down too low. unscrew, push the needle up as far as it will go, then tighten the screw.

if you are getting loops on the underside of the fabric or jamming around the bobbin, then your top thread is not under tension or going through the thread take up lever, that little arm that moves up and down. Recheck your threading path making sure you always raise the presser foot to open up the tension discs so that the thread lies into the tension discs fully. Also check that you have the bobbin threaded up correctly into the bobbin case, with the thread caught into the tension spring (you will hear a little click as it goes in). The bobbin will turn anticlockwise as you draw thread out of it. Use the top thread to raise the bottom thread up, replace the needle plate and bobbin case cover in place, then take both threads to the back of the sewing area. Hold them firmly as you start sewing! very important that you don't allow the thread tails to be caught and dragged into the bobbin as they will jam around the rotary hook.

try a new needle
rethread the machine top and bobbin
make sure the bobbin is not warped or damaged
make sure the bobbin is inserted in to bobbin case correctly
clean under the needle plate and in the bobbin area for lint
if the problem still happens,, then it would be a good idea to have the machine checked for a timing problem

try changing the needle
try rethreading the machine top & bobbin
make sure the bobbin is inserted correctly into the bobbin case, some
bobbins only go one way.
clean under the needle plate & in the bobbin area for lint & threads

there are a couple of things that come to mind.  
Bobbin:   wound with uneven tension.  Try taking the bobbin, rewind that thread onto another bobbin and wind slowly.  make sure the thread feeds onto the new bobbin evenly.
upper thread:  catching on something or not flowing off the spool easily.
you're doing well, sounds like you consulted the manual and used your noggin, hang in there and let me know if this doesn't help.  we can troubleshoot some more!

Amy,
did you solve the problem with your Jubilee?
I would suggest that the problem may be not holding the two threads at the back of the needle plate with starting each new seam. Elnas really need you to hold the threads, don't let the tail get caught and pulled back into the bobbin holder area. Once you have one jam, you'll have minute threads you maybe can't see caught under the ring guard (black bit) and the jamming will keep happening. Also, make sure you only use Elna bobbins always with holes on the top.

If you've still got the Jubilee and are having issues with it, feel free to add more info, the other contributors comments about the bobbin being faulty are valid but I dont think your machine is worn out, just jamming. You can remove the bobbin holder yourself and clean underneath it and once you've done it once, and know how to line it and the ring guard back up, its pretty easy and will ensure that the bobbin area stays clean.