remove the rear panel inside the oven so you can access the fan motor.the fan should turn freely.if it doesn't you can try and free it up by greasing bearings with thermal grease.if the motor has seized or one of the bearings has collapsed you will have to buy another motor.if you had stated make/model I could have told you where to source the motor and how much it was likely to cost.
ozone, December 2011
