Dometic roof are motor shot. How easy to replace?

I replaced both of mine last year. The actual install was no problem take out 1 and replace with the new. I used a friends shop so I had access to a hi-lo on the 1st one. the second one I just used a long ladder at about a 30 degree angle and hoisted it up while a friend pushed it. We did have an escape plan so no one would get hurt. It is not difficult and we did it in under 2.5 hrs.