Originally Posted by manicmike

Firstly, I assume you have it threaded correctly, that the needle is in correctly (flat side left) and that you are threading right to left. Skipping stitches is the strongest sign of threading the needle from the wrong direction.
Given that you have, did you remove the bobbin case and clean out the dirt and possibly thread from underneath? If you have, have you checked the hook timing? If you have (and to be honest I've never seen a 201 with incorrect hook timing) have you checked the thread tension? With the presser foot down pull the top thread. It should deflect the needle before the thread moves (but not break it). The bottom thread, when pulled, should always have less tension than the top thread.
Your problem sounds like there is no pressure from the tension discs at the top. Without any tension at the top, the bobbin thread pulls the top thread underneath the needle plate (also called the slide plate).