Chosen Solution
When replacing the home button on my iPhone 4 I ended up with a small rubber ring about 4mm in diameter. Can’t find where it goes.
Resolved it. Feel like a bit of an idiot, fell off one of my tools.
Your question is a bit confusing. So I will tell you about black foam gaskets on iPhone 4, maybe this is what you are describing. There is one on the Back Camera Flash, and another on the top front of the iPhone on the sensors.
