Might have mentioned that mine is a Model 1947 (model #, not year) Zig Zag, and it does have adjustable pressure for the foot. The only way I've used it is to release the adjuster entirely when trying to put really thick work under the foot – makes it easier when I can push the foot up with a pinky. When the work is in place, I push the adjuster back down.
The machine sews a whole variety of different stitches, not just a zig-zag.
Since I don't do decorative sewing, it is more than enough for tents, packs and other gear. When the work is too thick for the motor to power the needle to penetrate, I use the wheel on the right end of the machine. Crude, but it works.
Also experiment with different needles sizes, points, thread tensions and threads before sewing thicker work. It will not sew the heavier threads, like C&C Button and Carpet, or the heavier Gutermann, but have had no need for them – they are overkill.
The only thing I don't like about it is that you have to hold down a lever with the right hand to sew in reverse, making it hard to keep both hands on the work, although I've tried. Same problem when using the wheel to push the needle through, but that is seldom necessary.
The rheostat on the pedal in also some kind of ancient thing that sizzles when it gets hot – spliced in a modern one from a Brother, but when the Kenmore eventually went to Sears for maintenance they reinstalled one of the older pedals and kept the Brother. Still sizzles, but no electrical fires yet. Maybe I will pick up a better pedal from a sewing store and resplice it in.
