There is an adjustment for the shaft in the service manual - you can get a copy on line for about $10 - it is a service manual opposed to an operator's manual. I was able to move it around but my machine seems to have a slight bend in the shaft. When was that machine last thoroughly cleaned? I like to wash all the old gunky oil off them. Billy has info on that on here somewhere for the older machines. For that one, there are parts in the zigzag that sometimes get stuck up with old dried up oil. The kerosene wash could free up the zigzag part if that is what is stuck. Since it is electric you have to just kind of paint on the kerosene and keep towels around to dry it off. If your needle is hitting side to side it might just be gunky oil. Sometimes a bit of heat directed at the zig zag part of the shaft will free it up too.