I get a lot of 'bobbin thread break' when in fact it hasn't....so maybe the magnetic bobbins would be a help. But just ordered a half dozen gross of the regular bobbins...so that will be awhile before we can switch! Anyone else having trouble with BLACK bobbin thread? It breaks so often and thickness is so variable from one spool to the next we gave up using it-couldn't keep taking the time to readjust tension on every single bobbin reload. Heard from a tech that it is a known problem, just with black...