I went outside about 90 minutes ago and saw that the plastic bag had a leak. I guess I should have been more careful when putting the center inside of it. I decided to open it up and see if the cooked on material on the lid and center section had softened and I am sorry to report that it had not.
I took the grates and door out and sprayed them thoroughly with the pressure washer. The grates were partially immersed in the ammonia mixture and the parts that had soaked rinsed pretty clean but not enough to satisfy me. The interior portion of the door also partially cleaned up but, again, not enough.
I then took the sprayer to the center and lid and, again, there was some cleaning happening but nowhere near enough to justify the process. The metal grate holding brackets cleaned up much like the grates but the entire interior of both the lid and center section are going to need scraping and scrubbing in order to really be clean. Looks like I know what I'll be doing tomorrow morning.
Oh well, it was worth a shot!