hey guys ive worked on a pitco fryer a few times. and i notice it is starting to soot up a little.
it is a

this fryer runs on natural gas. i have verifyied the pressure is at 4.00"
it seems to burn ok. they did tell me once in awhile at lunch it will go into heat. which if i understand correctly just means the pot is not hot enough to cook yet. so i guessed maybe they put down 2 baskets of food at the same time, but im not sure. i suspect the soot is starting to insulate the pot so the heat is not transfering well.

my queston is, what is causing this? ive cleaned the burners about a year ago. could the burners be bad? to look at them they seem fine, but maybe they are not correct. (warped or something)

hope this makes sense.

thanks in advance