MGS587OADQ When oven is set to bake, say 350degrees, at about 150 degrees there is a slight popping sound lower right, like a dirty gas jet attempting to ignite and a faint gas odor. These disappear at higher temps. Since this is a convection model, I can't remove the oven bottom to see what's happening. How to correct this slight gas leak at ignition? Any clues? Thanks, Nick