Lower looper. I have threaded my machine properly, I think, but the lower looper keeps coming

Question

I have threaded my machine properly, I think, but the lower looper keeps coming unthreaded. I have rethreaded about 10 times very carefully. each time it lock stitches for 1 second and then stops. The strange part is that the thread appears able to escape from the needle hole without breaking. The machine works for about 1 cm and then no longer "braids" the threads. they just string along getting longer at the back of the machine