A. If the bobbin thread is just lying on the bottom, either the top tension is too loose (not pulling it up) or the bobbin tension is still too tight (keeping the thread underneath). So Fine! #50 is usually the easiest of all threads to use, when it comes to longarm quilting. We recommend trying the following scenarios. Please try scenario A) first, then B).
A) Tighten the top tension more and see if that will pull up the bobbin thread.
B) Switch the bobbin thread to So Fine! #50 also and see if that fixes the problem.
We also recommend the TOWA bobbin gauge. It's a great tool to dial in to a specific tension and is very easy to use. Whether you are winding your own bobbins or using prewounds, the TOWA gauge will work with any M-style bobbin (which is the bobbin style for your Gammill Classic).