I have cereal from petglider but will be switching to pro pets "happy glider" next purchase. The gliders rarely eat the cereal, they stay on the main food source.
I have the veggie and fruits like you, but I also provide critterlove complete.
That last part of diet is what I think you need to look into.
I have read here some people provide chicken or eggs or turkey as a protein source.
Our gliders also have that cracking in fur depending on how they stand.
I think you need to look more at color and softness.