My Crown Point SZA 645FL wont sew zigzag stitches?

The machine was in storage for many years and when I unpacked it I found although the motor ran, it had ceased up and the needle would not move. Took off the back panel and sprayed machine parts with WD40, including the feed dog assembly and bobbin winding assembly and subsequently managed to get the needle/straight stitch and feed dogs moving and bobbin winder working. However, the zigzag stitches don't stitch as they should. How do I resolve this problem please?