Wow, what a deal! I have two Elnas, I use the 6003 for travels (my 730 stays home!). Sometimes the bobbin doesn't wind as tight as I'd like, so I might put a finger on the spool from which the thread is coming, kind of slow it down a tad. That tightens it. Another option is prewound bobbins. They work fine in both my Elnas. BTW, LOVE them! They are work horses, and very easy to use. Just take them in for a cleaning once in awhile.