It was relatively easy to replace it. Some suggestions:
1. Make a platform to support the oven when you slide it out of the cabinet. Make the platform sturdy because this thing is heavy. Make the platform the same height as the cabinet so that you can just slide it out and back in without having to lift it.
2. The fan is secured with about 5 sheet metal screws plus there are 3 screws on the top that the fan slides under when you loosen them. However you can't fit a screw driver in the space to do the job. I had to use a plier to grip the round head screw and loosen it. That was difficult and took a long time. When I put the new fan in I replaced the 3 screws with hex head screws so that I could use small wrench to tighten them.
3. Of course turn off the circuit before you start.