Could well be just an element.
I am assuming that it stays in pre-heat while doing this.
Turn the oven to broil does the broil element work?
If yes
Turn the unit to bake, on most units they switch back and forth between the bake and broil elements.
Does the bake element work?
If one of them does not come on, remove power from the unit.
This is very important because many units still have 120 volts on the element even when the element is turned off.

Undo the screw/s that hold the element to the back of the oven and gently pull it into the oven.
Then check it with a meter should be around 10 to 20 ohms.