You still have the issue of how is the thread from the top needle passing around that "external" spool. If it doesn't pass all the way around the bobbin thread (or spool replacing the bobbin), you don't get a stitch.
I can't draw worth beans, but have a look at this. Blue is top thread, red is bobbin. See how the top thread made a loop, passed around the bobbin, to end up as a small "tack" across the bobbin thread. Doesn't work if the loop can't pass around the entire spool. Second picture - green is your thread extending to a spool - it prevents the blue from looping around the bobbin.
[ATTACH=CONFIG]375248[/ATTACH]
[ATTACH=CONFIG]375249[/ATTACH]