I purchased a new natural gas barbecue, but three of the burners won't light. The fourth burner, which is a back burner, lights just fine (and my old barbecue worked just fine, too). Although I have a half inch gas line in my patio, I am told there is a reducer on the line, thus creating a 3/8 inch opening. The retailer of the gas barbecue says I need to get a plumber to have the reducer removed and the 1/2 inch opening restored. The barbecue won't work until I do that. Others tell me that the purpose of the reducer is to increase pressure and that any barbecue should work. Can you shed any light on this issue.