Bailey your my hero! You were spot on with the issue and the solution. Thanks. The top sensor was ever so slightly stuck - a quick tap and it is doing it's thing. Now I ask do you think that this would be related to faulty part or perhaps a slight grease build up?
The area was dry and clean but we do stir fry a lot and use a pressure cooker often which generates a lot of steam under the unit.
If I wanted to get a few replacement sensors do you know the FRU# or where I could get them assuming Jenn-Air did not have them as my unit is end of life already.