What size are the threads that join the 24-in and 36-in wand to the quick connect?
The threads that connect the wand to the quick connect are 1/4 inch in size. You can purchase the replacement quick connect for the 24-in and 36-in wands here One-Touch Quick Connect Coupler for SurfaceMaxx Wands - SurfaceMaxx.
If you need a replacement coupler today, you can purchase the SurfaceMaxx 1/4-in Quick Connect Set in the Pressure Washer Parts department at Lowes.com. You can use the coupler in the set as a replacement coupler for the wands.