Donna,
Here is a manual for you: {
http://pages.sewing-machine-manuals....922443092.html }. Not free but of excellent quality.
To release the ZZ controls loosen the little lock just above and to the right of the stitch width lever. Right at the top of the machine. That lever needs to move to the "0" side for straight stitch.
At least that's what it looks like from the picture on Relics.
Joe