Sandra,
A few times my machine needle has gotten a sticky with fusible on it too. What I do is put put some rubbing alcohol on a piece of cotton batting and clean off the needle. It works pretty well. One thing I remember from my chemistry class - many years ago - is that alcohol is a universal solvent. It dissolves a lot of gooey, sticky stuff.
However, since this fusible has glued up your bobbin case, I personally would not try to finish machine appliqueing the pieces that you have already fused with the bad stuff. In my opinion, it is not worth the risk of damaging your sewing machine.
Let us know how it goes.
Judith