Annnnnd... I got the roller door. The demolition crew are nice guys. I'm making a small storage space extension at home, and it needs a roller door. By chance the side roller at 888 is about the right size, and hopefully if can be made to fit. I asked the crew if I could salvage it, and they said yes. Started 7am this morning, out of there by 9:30am. They expect to start dropping that building this afternoon.
One lesson: DO NOT release the winding spring tension in a big roller door, before tying the roll securely so it can't unwind.
That was a very spectacular and loud mistake. Oh well no serious harm done to the door, only to my pride. It definitely wasn't part of the plan, but it did make it easy to take apart section by section. Instead of lowering it all rolled up - and very very heavy.
The 'monitor room' is finally empty.