As I said above, I remounted mine last night.
The old mount was one of those cork slabs (lumps of cork stuck together into slabs). It had
totally disintegrated and I decided to remove most of it. It just fell to pieces like removing decomposed bark from a potted orchid. The roots were running all through it, you can see below all the roots that were inside the cork of the mount. Because it fell to pieces so easily they weren't really damaged by removing it.
The new mount is a solid piece of cork bark that I bought in the pet section of my garden centre (sold to go in vivariums). I mounted near the bottom of it, because I know these orchids are likely to climb. I put some sphagmum in the places there was a large gap under where the plant sat and where the new mount is.
I was also careful to leave the front surface of the old mount and it's covering of live moss. This live moss has grown there from a tiny spot of it when I first bought the plant. Max seems happy enough with it there and I like the look so left it.
I'm pleased with the result. I hope it settles onto this new mount well.