my janome doesnt have the elliptical thingy but does have a screw place more room between the fill lever and the bobbin in order to get more thread on each...i also when winding bobbins, use 2 fingers from my other hand to actually move the winding thread up & down in order to distribute the thread more evenly...it keeps it from filling the center only which sets off the fill gauge which shuts down the process...1 more thing is i have a clear large pill bottle that i have put a hole in the bottom and keep 5 filled bobbins always ready on my extra spool spindle...when i run down those 5, its time to clean out the bobbin area & put a drop of oil on the wick...just a little schedule to help clean out the dust & lint which builds up...some fabrics and threads are worse than others at leaving deposits behind....monica in texas...

I also have a sidewinder and always have a spare bobbin loaded and ready to go. Nothing more frustrating than on the last seam when you run out of bobbin thread.

I use my side winder too.....great little invention.......why didn't I think of it!!!!

I stopped winding my own when I found Superior Threads pre-wounds.
They're wonderful and last forever. I pieced a twin top on one bobbin of Bottom Line.