We had one fitted for MIL on one of the staircases, two rails with quite
complicated curves. It hasn't been used since she died a few years ago,
I am inclined to leave the rails in place but it would be nice to remove
the chair, until next required.

They seem to be cunningly designed so that only their approved
contractors can work on them (e.g. I'm buggered if I can see how to get
the batteries out to replace them).

I thought at first that the seat might "lift off" after removing the
constraints, but it looks to me as though you might need to wind it off
at the top, after removing the fairly simple "stop". Anyone know if this
is correct?

I've made a tool so that I can hand-wind it with a brace (and possibly
with the cordless drill) but before I take it up to the top it would be
nice to confirm if this is the way it is done. Otherwise I could see
myself ending up with a landing and stairwell full of ping-****its.