Hi,
This may help:
23 Hamster Behaviours 🐹 - YouTube
It just explains signs of stress and what to look out for. Also, I think people get hamsters balls wrong thinking because they run in it = they must be happy. But if you think if you’ve been put in a tiny room you’d try and get out. They’re running more because it’s the only thing they’re able to do. They have very poor eyesight and great hearing so bang into walls which stresses them out more because they can’t see, and hear the bang much louder. They also can get their feet trapped.
Hamsters tend to be quite skittish so I wouldn’t take this as a sign they’re unhappy if that’s what you’re confused with. If a hamster wasn’t happy they’d bite you so you’d know very quickly. Also pacing in the cage or bar biting is a clear sign they’re not happy with their cage.
Hopefully some of this has helped!