You may have to trim the fluff around the vents on both the roo and the hens, if it's so thick it's preventing good contact.
But I'd crack open a few eggs, and look at the white spot. (On the surface of the yolk, all eggs have one. If you don't see it, turn the yolk over) Is it just a tiny dot, or does it have a distinct ring around it? It the ring is visible, it's fertile.
I hate to say this, but...you're not looking for a blood spot are you? Those have nothing to do with fertility, it's just blood.