The way I explained it was explained directly from the Sonofresco manual. When programming profiles you must have a temp Rate of Rise of not less than 2.5degrees C per minute and not more than 25 degrees C per minute. I believe the way I attempted to stretch the roast I may have gone outside these parameters. This in turn I believe caused the E4 code.
Prior to roasting, (Which sometimes is only once or twice a week.) I make sure my roaster is CLEAN. All areas you photographed are in fact clean with the only difference is my Thermocouple is Stainless. Mine is new so it came equipped with a stainless one. Yours must be old enough to be equipped with an overly fragile ceramic type? Your comment on afterthought engineering tells me you have no intentions of upgrading to a stainless thermocouple. You may go through less TC's if you upgrade next time you have one fail but I'm a noob so what do I know? Now, the dirtiest part of my machine is the 24 inch chimney that points straight up with a wind blocker to prevent wind from being blown down into the TC which would sure cause an E code.
I generally steer away from forums because often times theres that 1 guy that his favorite phrase is "Use the search" or here we go again, how many times has this been asked and answered? So, I may or may not lurk the board, I may try and buy some coffee but the response I got regarding my friends pure Kona kinda put a bad taste in my mouth. I sure wish there wasn't an ocean between us. I would love to clean my roaster and then you try to get it cleaner. In fact, I guess I will try just for shits n giggles a screen clean using Citric Acid.