Dyna Glow Wall Heater - Will Not Light

Question

I have a vent free Dyna Glo wall heater. The model number is FP-65 NGT. I have disconnected the gas supply and verfified that I have gas pressure going in to the wall heater. But the flam will not start when I engage the pilot. It doesn't light either if I hold a match to the gas outlet at the flame location.Can I have an obstruction within the wall heater tubes? If so how do I fix the problem? Compressed air?Thanks, John