Does that mean you have a wodent wheel? Wodent wheels are not considered safe for glider use due to the axle and solid track. Both of these parts get dirty and sticky very quickly due to the gliders going pee and poo in it while they run, and if the glider's tail was to get stuck in the axle then he could potentially suffer a tail degloving, among other injuries. Also, the tail and/or limbs can get caught in the axle causing the same injuries; supposedly they came up with a cover for the axle, but that only makes it so there's even less space in the wheel for them to run in. Another issue is that if there's a glider trying to use the wheel while another is running in it, it could be injured since the wheel is not high enough off the ground.
This is just to mention some of the issues reported regarding this wheel. It is my recommendation that you replace this wheel (you could reporpuse it as a ball pit) and instead try some of the wheels listed in the link below:
www.sugarglider.com/gliderpedia/index.asp?ExerciseWheels
Another good one is the H-Wheel which has a speed control system:
www.humbertossugargliders.com/H-WheelFAQ.html
In any of those wheel, you can install trim tracks, which are sand paper strip placed on the exterior of the wheel, serving the same purpose that the Nail O Matic does. You just need to replace them once they get dirty, and because is in the exterior it means that your gliders nail will keep at a certain length always. If that is still a little too long for your comfort, you can try to clip them yourself using nail clippers. I do this every 2 weeks or so, or whenever their nails feel too long for me.
Hope this is any help.