I have a Heatilator gas fireplace that I can't get started. Fireplace was working fine until we had a gas leak at the meter outside our home. After the leak was repaired and the gas was turned on again I tried to get the fireplace going. The gas valve is on, I am turning the pilot knob and holding it down which pressing the ignitor. Ignitor produces a small spark at the tip but the burner won't light. By the way, I was able to light two other fireplaces in the house without isssue. Any help is appreciated