I have a Jenn Air Model SVD8310S The gas top burners were converted to propane by the propane company when I built the house but I am getting Natural Gas and would like to convert it back. I think I found the orfices but don't know for sure where they are and if you just change them or need to adjust the pressure? The orfices seem to be two of one size and two of another not sure were to fide the old ones and witch to replace with witch. Thanks for any help or even the conversion instructions.