First of all, you've got a great machine! I'm using my mother's 158.17740 for everything but foundation paper piecing (the stitch length won't go lower than 12/inch). It can sew through anything.
You absolutely must have a manual for this machine. I'm constantly referring to mine for the simplest things. You can find them online (Model 1774 Zig Zag Sewing Machine). Also, go to Yahoo groups and join the Vintage Kenmore group. It's a private group, so you'll have to be accepted and you'll have to get a free Yahoo account (e-mail) to join. But they're a great and helpful group with all the answers.
As to your cam problems:
When turning the hand wheel manually, always turn it toward you. Turn it so needle is at its highest position.
When you insert a cam, you have to be sure it's in the correct position for the start of the pattern. There's a hole in the cam that fits over a pin on the left side; the cam must sit down as far as it will go. On the right side is a lever (what they call a "follower") that must align with the dot engraved on the cam. The manual says, "To do this slip the cam onto the shaft so the engraved dot is as near the cam follower as possible. If the dot is not aligned with the follower, turn the hand wheel toward you until the dot is aligned."
Aside from that, for the Basic Decorative designs, the Special Stitch Dial will be set to CAM. Stitch Length: Red Zone. Stitch Width: 1 to 4. Special Stitch Modifier: Red Dot. Use the Satin Stitch foot and the Zig Zag hole on the needle plate. (22, 23, 24, and 30 are Reverse Stitch designs with different settings).
Good luck!
Last edited by CookyIN; 09-05-2015 at 11:24 PM.