I have had the same problem ( D81005d ) and have also replaced the 3 thermal cut outs located under the top oven panel.
Recently I noticed that closing the top oven door sometimes resulted in the bottom oven restarting so I wondered if it was just a loose connection. On pulling the thing to bits again I failed to find any loose connections but discovered 2 further thermal cut outs ( 180 degrees ) mounted at the back of the ovens. I have just ordered replacements and will update on success / failure once they have been fitted.
Golfalottoo, October 2009