Kenmore Sewing Machine 385.16120200?

When sewing, I can go about 2 stitches forward (length 2, width 6.5) before the machine makes a knocking noise and the fabric is pulled down into the machine. I push it, I have gotten it to go forward more than 2 stitches, but it still knocks every few & tugs at the fabric. When the knock happens, I can see the needle pulling slightly to the left. When this is happening, stitches aren't being completed; the thread is all knotting under the fabric.

I have tried taking the metal plate off, cleaning & oiling & ensuring nothing is stuck underneath. I don't know what else to do. Suggestions?