Pain points can be related to the effort to do something (e.g. finding the first paying customers) or the experience of doing something (e.g. using Google Drive for knowledge repository. We all know that's a mess!)
"Bring people around *value* - some common utility that solves their problem." - Erik Torenberg
The best way to identify pain points of your community members is by speaking to them and asking the right questions.
Your main goal is to understand their problems so you can help address them through the community. Talk less. Listen more. Visualise it like you are facing the problem yourself. It also helps immensely if you experience or have experienced these pain points yourself.
Some specific questions below to help you uncover the pain points:
"The strongest communities are built around a pain or struggle that people feel shame around. Identify a pain that people are experiencing, and create a space where they're accepted because of that pain. Give them a place where they don't have to feel shame." -David Spinks
The Mom Test - this book shows you how customer conversations go wrong and how you can do better.