For a counterbalance loom you tied the cord to hold the lease sticks to the frame and the back beam. Where do you tied the cord on a jack loom. If you tie the cord to the frame it must go around the edge of the harness.
I nudge the heddles over a bit and put it in the same place...you don't want the cord encasing the heddles because then you wouldn't be able to thread them. Hope this helps.
Here's where I put mine, around the uprights, just above the harness guides: https://ibb.co/Qk23rpF