I think Dryer is probably right--a tiny piece of thread is stuck somewhere in the bobin assembly. They can be a real PITA to find but easy to fix. I understand your frustration--been there done that. Thankfully I didn't throw the machine away--just let it sit for a while then went back to it and finally fixed it. IF however, you do decide to part company with your Elna I would be delighted to have it and would be willing to pay the postage and packaging <img src="/forums/images/graemlins/grin.gif" alt="" />. Also go back to the manual and make absolutely sure you are threading the machine & needle correctly, winding the bobin and having it loaded correctly, and the needle is installed correctly. Super simple but you would be suprised how many machines I have "fixed" by studying the manual and going through all of this step by step.
My advice is to keep the machine just because of it's history even if you can not ever use it to sew with. Good luck.