Hello,
Thanks for the replies!
I did get Elna specific bobbins - but interestingly enough they're very tight on the winder spindle. Really have to work to get on on all the way and when I pulled it off the shaft came along with it.
Timing - could be. No research thus far has addressed timing adjustment.
Bobbin thread pulling more loose than top thread - I wonder if I have it threaded through the tension spring properly despite the videos and book larnin'