My step-mom just gave me her old Brother LS-400 sewing machine. Now, on every other sewing machine I’ve ever used, I could figure out how to get the bobbin to do it’s thing.
But this machine . . . I hafta take off a chunk of the base to get to where the strange metal bobbin-holder sits. Once I manage to get the bobbin in to this contraption, put it back into it’s holding place, snap it in all securely, I still don’t know how to get the thread up to where it needs to be to do its thing.
Please tell me someone out there has one of these machanized bastards.
I have no idea what’s going on. 
Thread the machine in the usual way. Holding onto the top thread that is now about 6" beyond the needle, turn the flywheel one rotation TOWARDS THE FRONT OF THE MACHINE. This should bring up the bobbin thread. If not, make sure you have the bobbin seated correctly and securely. Do you have the manual? If so, refer to it. If not, check out www.sew4less.com, they have machine manuals. Good luck.
The bobbins on the Brother machines are incredibly simple. You pop the free-arm thing off, and open the little hatch where the bobbin lives. On your bobbin case, there’s a little flap-looking thing. You flip that forward to unlock the bobbin, and it pops right out. You just pop your wound bobbin into the case, leaving about six inches hanging out, hold your little latch out, and pop the case back in, making sure that little arm thing is sticking straight up. Release your latch, and the bobbin is locked into place. Now thread the machine, leaving six inches or so of thread hanging out past the needle. Hold the thread end firmly, and rotate your handwheel toward you, so the needle goes all the way down and comes all the way back up. Gently tug the thread end in your hand, and that will pull your bobbin thread up where you can grab it. Unless the machine is majorly malfunctioning, that’s all there is to it. (You have to make sure you’re leaving enough thread for the mechanism to catch, though, or you’ll never get that bobbin thread up.)