I'm sorry it took so long to get a reply.
My Lulu overgrooms, here is pic of what it looks like so you can compare. This is a recent photo, just taken yesterday. Her bald spots will grow back, I noticed that it is improved when we get into and keep a regular "out of cage" play schedule. Unfortunately, I often find myself getting out of the routines for extended periods since my first move across country, because I haven't actually gotten settled enough into life adjustments and then illnesses to maintain any for too long. I'm really hoping to fix that soon.
Anyway, so Lulu has always been my more "neurotic" personality glider, while Skadoosh is more laid back for the most part. Ollie, is somewhere in between the two personalities, lol.
If it's overgrooming, it is likely related to stress. Some gliders are more easily stressed than others. If you can identify her stress source, you may be able to help reduce it. As I found that spending routine out of cage time with my babies helps with Lulu. When I first noticed it, I called the glider vet closest to me at the time and she spent some time on the phone asking questions and making suggestions. It took some time for me to identify the main cause stress factor for her, but I eventually did.
Good luck. And please keep us updated on how he's doing.