I find that most all of the tube cages are designed way to small for a syrian hamster (at least I have yet to see something suitable) I also heard that most syrian hamsters do out grow their cages.
In my personal opinion these cage designs are /way/ to small for a full-grown syrian hamster (not just the rubes). Perhaps you might want to look into a larger cage, like an aquarium or a plastic bin cage, which is becoming a very popular way to house rodents in. I wonder if maybe the tubes are posing a problem and perhaps the hamster if bored with her cage?
If shes eating a drinking thats a good sign.. if her eyes and nose look clean thats good as well. Does the hamster get much out of cage time during the day? Is it possible that maybe shes getting to much excitement during her normal sleeping hours?
If you have room for a larger cage I suggest you look into it. Hamster Central has two articles about making your own bin cages if your interested. http://www.hamstercentral.com/generalarticles.php