Can you try this; with the compartment door open, hold the top thread with your left hand, slowly turn the machine advance with your right hand, and watch to see if the "hook" catches the thread loop and pulls it all the way around the bobbin case. If not, you might have to disassemble the "hook race" and clean out lint from the area above the bobbin case, (a small paintbrush is good for this) then reassemble it.
This is somewhat complicated, but it could be worth the effort; my machine clogs up here freqently, but I sew a lot of cotton, wool and linen, in between bouts of ripstop....HTH, Betsy