You have the same model I have--it is a 158.1941 Mine is low shank and was bought in 1976--They started making this model a year or so after I bought mine only with a high shank To get it to zig zag take top dial off red dot and put it on 4 for width--then move bottom dial to 10 or 12 --- the inside top dial should have the zig zag at the top-- it is a great machine!!! mine isalmost 40 years old and still works great