Caroline, we are so keen to know how it all goes with this resuscitation!
In my Elnas (or any machine, really), even a single thread caught in the bobbin business causes a disaster. The wrong bobbin (which by now others have pointed out to you as well) and even a cruddy needle.
I am really certain that underneath all that gunk lies a GREAT machine. You may indeed need a few parts or adjustments (well, the machine, not you!) but you are going to be SO HAPPY once it is up and stitching!!!
:-)