how can i fix my electrolux eob944?

i have the electrolux ebo944 model, i bought this second hand from a mate, he told me that if there is a power cut, you have to put the dial on cook or end time and adjust the time, something like that, otherwise the oven doesnt heat up. this did happen to me about a year ago and i managed to get it working again by the procedure above, i have since lost contact with the mate and the problem has occured again, and i cant remember the procedure to cure it? can anyone help?