L-344 loose stiching

Question

Machine is threaded properly. Proper needle for cotton is being used. Same thread is being used both on the top and in the bobbin. Bobbin is threaded proprerly. Tension dial is currently set on 3...but the stiches are loose no matter what the tension is. No matter how high or how low, the stiches remain so loose they can be pulled from the fabric without effort. I am stumped. Any ideas?