Didn't think that there was a steering lock on the 1966 +4 ??? There isn't one on mine anyway!
If it's seriously stuck then it should be possible to remove the switch from the dashboard and work on it on the bench (the barrel should remove easily)
Just one thought, when the switch is turned fully anti clockwise (in the aux position) the key won't come out. Have you tried to take the key out in each position of the switch?
(Looks as if my post was too late......)
Last edited by Malcolm T; 28/03/16 05:34 PM.