You wrote: I'm thinking I might have a burr somewhere along the line on one of my thread guides.

I am thinking the burr is not along the thread guides but on your hook assembly. If you have a burr there it will shred you thread everytime the top thread wraps around the hook to pick up the bobbin thread. Before you spend a lot of aggravating time testing your top thread path, carefully inspect your bobbin case and hook assembly. Often you can feel the burr or rough spot with your finger. You can file it down with an emery board nail file. You may want to check your timing while you are at it to ensure the needle isn't rubbing the hook with every stitch which may have caused the burr in the first place. Good luck and let us know what happens.