Thanks for the advice guys.
On arrival i was presented with a wheelchair lift that went through the floor !!! Result. But no, it was dead. Long dead.
Also there was a stair lift. This was also dead. The owner of this place had suffered health issues for years and passed away earlier this year. In the games room it led to was a full size snooker table, party zone, two fruities, a mountain of paintings, clocks, china ......
We had to remove the dead stairlift. This was surprisingly heavy ....
I went for a "risk managed solution". It was my first time down stairs so I was cautious.
I bought these 2 slings and a rope from toolstation. TOOLSTATION IS MILES CHEAPER THAN SCREWFIX, NEVER BUY FROM SCREWFIX.
I removed the head and transformer from the game to reduce its weight. Foam mat at the bottom. Me on the rope at the top with gloves. The owner steering the game by standing in the danger zone, he didn't have to bear any weight. It went down under complete control. Each step served as a gentle brake. No damage to either of us, the house or game. The only contact point for the rope with visible art work was under the coin door, so this was protected by some cardboard.
Home safely ...
Having done this once, next time I would do it with the head in place as the pin was very comfortable going down a carpeted staircase.
Thanks again to
@JMP for the tip off last night