I numbered the screws in the image for reference:

1: Pivot point for upper arm. Position this inward/outward to change the lever ratio and thus tension.

2: Removed this screw which held the arm in fixed position.

3: Travel stop in case the wire snaps. The arm is normally about 1/4" above this.

4: Spring attachment to upper arm. Predrill to avoid splitting the end-grain!

5: Spring attachment to brace. Choose this location to set the tension.

6 and 7: Fixed mounting for lower arm.