Not bent, not jammed, didn't hit the bottom with it. Ropes all move freely. It just stopped working of its own accord.
So today a little rudder TLC and whilst I was at it I made some adjustments to the tiller as well.
Firstly, I re-threaded the down-haul and moved one eyelet where it secured it to the base of the rudder tiller stock.
And hey presto, with that one small alteration, it started working again - go figure!
On the tiller, I moved one or two cleats to new positions to make handling of down-haul and up-haul easier, filled in some screw holes with wood filler and installed a new metal eye for the tiller tamer.
The old eye was beginning to cause the tiller tamer rope loop to jam - again for no particular reason I could discern - wear and tear I guess.
It's nice to potter for an hour or so in the workshop, aka the garage, doing odd little jobs. Makes me feel all happy and productive - how weird is that?