To remove it you need to take the back cover off and there will be one screw in the bottom center holding the heat exchanger to the case…
Remove that screw, disconnect the gas line, then disconnect (you may need to cut the wires, but make sure you mark them), looks like they were already cut once… now the furnace should slide out the back of the case…
If it won’t slide out or there isn’t room for that, remove the 2 back corner screws holding it to the floor and you should be able to slide the whole furnace back enough to free it from the manifold pipes… (it might be easier to remove the pipes from the outside first, that’s how I do it…)
Sound like a bad motor… they are quite expensive…