How do you fix an error 300 on a SWF embroidery machine?

The best way is to watch a training video like this on fixing an error 300 on a SWF embroidery machine. 

What is an ERROR 300 (Needle is not aligned over needle plate) and how to clear it

A. Press any needle number other than the one that you are currently using.

Every embroidery machine has error codes including Tajima, SWF, HAPPY and Toyota embroidery machines.