The spring of the plastic part

Hello, can someone help me =(((

đây là nguồn của bài viết trên iFixit:

https://www.ifixit.com/Guide/Logitech+MX...

I have trouble with Step 13 "Disassembling the scroll mechanism" when I don't know how to reinstall the spring of the plastic part, when I disassembled I didn't pay attention to it but it was attached, please help me.