I got the Fantasia all back together and was testing the different stitches. I got to the buttonhole settings and noticed the stitch length forward and reverse were different lengths so tried adjusting with the small screw on the back of the machine........ One of the few plastic pieces in the machine happens to be the eccentric cam to balance forward and reverse stitch length for the buttonhole. I'll give you one guess as to what happened.
All the pieces for the cam:
Now what do I do? Seeing as I have a lathe in the basement, first thing that popped into my head was I could try making one out of brass. That would have been a half-day project though. My next thought was to use J-B Weld but that material would take up space and probably not work well. My dear wife mentioned super glue, which I decided was the best route. But it also needed to be stronger than just glue, I thought, so I fashioned a washer to have the inner diameter fit over the plastic cam. Here's the result. Original washer on the left, modified one on the right.
Just one minor problem though, the washer was sitting right where a lever in the machine was supposed to ride for part of the buttonhole stitch. So, off with the washer and hope the super glue would hold.
Everything is back together and the machine sews great. The electronic foot control allows precise control for making even a single stitch, quite the feat for a machine this old and "mechanical". If you look at the buttonholes in the photo below, you can see the lower one has uneven stitch lengths. That was when the plastic cam broke. The upper buttonhole is after the glue fix.