Oven Light Not Working
Under normal operations the oven light should come on when the door is opened or when the oven light switch is activated. If the light in your oven does not come on when the door is opened, first test it by closing the door and turning on the oven light. If the light does not come on when you flick the switch, the bulb will most likely need to be replaced. The light is a standard 40 watt appliance bulb -- be sure to replace it with the same type of bulb. Never use a bulb that is not specifically designed for appliances. You may want to take the burned out bulb to the store with you to make sure you get the right size. If the bulb does not appear to be burned out the problem may be the switch on the oven door. If the switch is not being activated when the door is opened the light will not come on. Replacing the switch with a new one should solve the problem.
Uneven or Poor Baking
If your oven appears to work but bakes unevenly or does not heat the food the whole way through, it is likely that the baking element has begun to go bad. These elements typically last at least four or five years, but on occasion they can fail prematurely. Sometimes a baking element will go out all at once, making it impossible to bake at all. More likely the element will go bad slowly, often showing no signs at the beginning other than a bit of uneven heating. If the baking element is defective, it will need to be replaced. You can order a replacement element from the manufacturer or from the appliance store where you purchased the stove.
If you see sparks coming from the oven, immediately turn it off and unplug it. Do not attempt any troubleshooting until the oven has cooled completely. After the oven has cooled, be sure that it is still unplugged and carefully examine the interior for signs of damage. Look at the baking element, the broiler element, the burners and other areas that could have caused the sparking. If you find an obvious cause, you can replace just that part, otherwise be sure to have an experienced appliance repair person look at the stove before attempting to use it again.