I would take it completely apart. Rinse it off with hot water as best you can, then put it in your oven and heat it up to 250F or so. Carefully take it outside or someplace where you can spray it down with Heavy Duty Easy-Off Oven Cleaner. Get the more potent version of the Easy-Off and not the fume free wussy stuff. Follow the directions on the can including how hot to warm it up. I was guessing at the 250F temp. The directions may well call for something different. I think they suggest pre-heating an oven before applying the stuff. Something like that.
Wear gloves and eye protection. The active ingredient in the oven cleaner is usually lye and it can be hazardous. Do not get it in your eyes under any circumstances.
Rinse and repeat as necessary. Use a small drill bit to ream out any of the gas ports that may be plugged up. Blow it out with compressed air if you have it available. Otherwise, just air dry, reassemble and you should be good to go.