There are three reasons for the decorative stitches to not work. (1) The stitch selector lever gets gummed-up. Which is an easy fix for a tech who's not afraid to use a little WD-40 on that shaft. (2) Or the camstack gear is cracked. (which can be replaced, but is $33 + labor -- not an easy fix). (3) Or the needle bar shaft needs to be re-positioned -- another easy fix. I'm thinking it's #3, because you're not getting a zig-zag.
YES! This machine is worth putting the money into! I just inherited one, and am working on getting it set up for our family business.