This is the foot control we use, and attach to the Bernina cord at the shop. Part #072963 Singer 1116 2662 with 771 cord Here's the same foot control that's connected to the cord, at a great price.
https://www.ebay.com/itm/Complete-El...-/321973575036 The cord by itself retails for $45! Last time I checked Ebay for these, they were selling for $100.