Why the Taptic Engine making my iPhone 12 rattle?

So I changed the battery and the Lightning port Flex on my iPhone 12 and upon testing the functions I hear a really bad rattle. It's not the Taptic Engine itself, it's another part/parts that are vibrating by the Taptic Engine. The awful noise goes away when I put pressure on either the Engine or the battery. Does anyone know what part could be causing this? I have also removed some parts like the speaker and sim card tray to pinpoint what the problem is but I really can't figure it out.