Installing a new motor on a atwood furnace

[Northwoods Camping Supply]

I am putting a new motor into a atwood furnace. I have everything torn apart but I am wondering if someone can tell me how I go about removing the combustion wheel off of the old motor. Do I have to use a puller to take it off? or should it just pull off by hand? Everything behind that wheel is plastic so I have no clue on how a puller would work and not break the plastic behind the wheel. Thank you.