Heddle bars on the Cricket Quartet are very sturdy and should not bend easily. Replace only if a shaft frequently sticks inside the castle.

assembly manual for Cricket Quartet

To install, you will need a rubber mallet and the assembly manual for the Cricket Quartet.

1. Go to the section "Assemble the Shafts" in the assembly manual. It explains how the shaft goes together, and how to secure the heddles so you can reinstall them later. Follow directions to tie heddles into a bundle so you can reinstall them later. 
2. Go to the section "Connect the Shafts & Levers" and work backwards through its steps to remove the shaft from the Quartet.
3. One wood side of each shaft has a dimple (the free side); remove it. Remove the heddle bundle and if necessary the lever cord. Remove the damaged heddle bar from the fixed side of the shaft.
4. With a rubber mallet, tap the new heddle bar into place on the fixed side. Make sure it's fully seated in the fixed side, so the shaft will fit between the castle sides.
5. Replace heddles and lever cord (if necessary). Reattach the free side of the shaft.
6. Reinstall the shaft and reattach the lever cord, as explained in "Connect the Shafts & Levers".