Probably the easiest way is to pull the furnace out of the mh and do it on a bench. To remove the inner parts you have to go through most of the steps it takes to remove the whole thing anyway. Mine is beneath one of our dinette benches, so I unscrewed the bench top to access the furnace. Unscrewed the plenum plate across the back and found two screws holding the housing down to the floor and unscrewed those. Disconnected the ducts on the side (the collars just turn and release). Went outside and unscrewed the vent cover (4 screws) and pulled it off. (You kind of have to pull with a rocking motion as the vent tubes are inside the furnace tubes. Once the cover was removed, another screw to the floor was taken out. I then disconnected the gas line on the left. Then disconnect the four wires. I wound up cutting the wires and putting connectors on them so if I have to take it out again it will be easier. Then the whole thing will pretty much slide right out the hole. They aren't very heavy, probably 20-30 pounds. Once it is out where you can look at it, it will be obvious how it comes apart...it's pretty basic.