Rumbling noise when using convection bake or roast

Turn off power. Remove 4 screws holding the fan cover inside oven using a 1/4 in. nut driver. . Hold the fan from turning and remove the nut by turning clock-wise(left-hand thread!) using a 1/2 in. nut driver. Then from the back of the range, remove the sheet metal cover to expose the motor(1/4 in. nut driver). Remove the 3 screws holding the motor(1/4 in. nut driver) and pull it out. The new motor comes with a seal, so don't forget to stick it on. Put everything back in reverse order and your done. Nice and quiet after that.