If it was me, I might take it to a repair shop or person who has a sewing machine bone yard, and try a few things. Or, you could buy a whole other machine just like it, just to have for parts. I'm looking at my Dressmaker, and comparing it to my Kenmore, and the lever on the Dressmaker is thicker where it attaches to the machine. It will need to be the right size/shape to engage the tension release.