New stove is in the garage, it’s final location is up one step then down a dozen. In the past I have called a few buds and we carried it down. Now nobody wants to come help when I ask! Lol. I don’t think the slide will work out too well.
Remove the slide, replace with 3 - 2x6 boards, tow straps securing the stove to your vehicle, one person back up slowly another person guide the stove (from the top/behind the stove) and lower to the basement. It'll work, did it with more than one appliance!
How close are you to Littleton? We've got heavy duty dolly's we use. One guy on bottom, one guy on top holding the dolly.
And take the door off and firebrick if it's easy to put back to lighten it some. Also I hired a place with a mechanical stepping dolly to get our gun safe down stairs.
So nothing to anchor to up top? No door or window to run a strap through? 2x4 across the opening, tie a trucker strap to it, use that as your winch to lower the stove down the forementioned boards/slide... More pics of the area would help us help you...
Once it is at the bottom, 2 wheel dolly, or 4 wheel cart for sure! Or rolling it leapfrog style on a couple pieces of 3' ish long pipe works well on concrete too...
Probably an escalera. They are pretty much the industry standard stove cart. They have a power stair climber.
Dad put a door for 2x6 construction in a 2x4 building. That might require some blocking so I don’t rip the door out of the wall!
This is a stove, not a truck...you may be surprised how little it takes to keep it from sliding down the boards. Setting it on a pallet in front of the Bilco lip is dead on. You will probably want one other person to help make sure things don't get hung up and slide down in a well controlled manner.