Need Help with Brother BAS 415

Rita

I have had my machine for about 5 years now and we have readjusted the timing several times so we have a good idea as to how to fix that and how to set the tensions but the last couple days we are having a problem we never had before. The machine will sew but breaks thread and no matter where you set the tensions on either the bobbin or the upper it will not show bobbin thread. The hook does not have any scratches and there doesn't seem to be a problem with that, we have readjusted the needle bars as well with no success. The only thing I can see that may be an issue is that the hook is not center to the scarf of the needle but it is extremely hard to see the scarf. If anyone knows what could be wrong please let me know asap. This is driving me crazy.