Griddle Unit not in use. Removed front panel. Pilot is lit. Turn on gas thermostat. Burner did not light right away. When it did it popped. Can see the flame is wavy where the pilot crossover tube is. Checked gas pressure. 4.3" wc nat. Adjusted to 4 " as per data plate. Removed thermostat. Checked orifice. It is OK. Compared it to the right orifice. It was identical. The right side is OK. Reassembled all. Made a slight adjustment to the thermostat. Also, the air shutter was not open enough. There was some yellow tipping. Opened further. Turn on thermostats. Now the left burner lights right away and the flame is not wavy. The right burner is OK. as well. Back in service.