Mysterious Scratch Scabs on Chance

[M0onkist]

I cannot figure it out at all. He doesn't scream at any odd moments, Mr. Honeycomb doesn't SEEM to be the culprit, but Chance winds up with long thin scabs on his tiny person. If I accidentally scratch over where they are (usually because I didn't know they were there) he squeaks and wriggles and then I find them.

Usually when they fall off, they take some hair with them, and he winds up with sort of a thin bald patch for a while.

Any ideas on what might be causing these? As far as I can tell there's nothing sharp enough in the cage to do that kind of damage.

A photo of his most recent (and quite long, maybe 1.5 inches) scab (I wet the fur around it so you could see it better):

 

[jorats]

That must be the boys scuffling. Probably not fighting but having their play fights. Can you trim their nails down some? That might do the trick.

 

[henry's_mum]

I agree with Jo, looks like some minor play scraping wounds.
Oh boys will be boys!
Clip that hunk of manrats nails hun...

 

[M0onkist]

They are clipped now! For all that he's a hunk of a manrat though, he can be a real baby about a very gentle clipping (no quick or anything)!!

 

[jorats]

They can sure be big babies.