Just now I was in the bath as usual. As usual I pressed my thumb down on the 'elevate' button to get out. A few weeks ago I noticed that my thumb wasn't strong enough to bend while pressing, I had to kind of move it round so I was just pressing down, just with my hand muscles, no 'bending my thumb' was involved.
I noticed yesterday that it just works now, from any position, I no longer need to make sure that my thumb is at the 'pressing' angle