gas cooker ignition problem?

Got a problem with a cannon lincoln gas cooker at the moment, model number 10258g serial number 78 1 0085. When a press ignition button in, 1 hob is not coming on at all, other 3 come on after a number of presses, plus toaster struggles to come on. A council gas man who was doing a job at my house said it could be a problem with the battery. Does say on bottom of cooker about a 1.5v battery but (a) do not know if this battery is connected to ignition and (b) cannot find a battery on the cooker anywhere.