Steve.....Many thanks for your response. I had the car out yesterday and as yours my 3rd and 4th are in the centre of the box with 1st and 2nd off to the left. Once you know this the gear change is fine. I think the problem is that unlike before I can move the stick to the right beyond the 3rd and 4th input. Before, the gear shift came against a stop while moving to the right and straight up for 3rd and down for fourth. There was no need to "feel" for the slot. I am suspecting the pins that go through the tower into the slot on the ball of the gearstick. (and hold the cap down). They look ok but possibly the right hand pin has moved out a little allowing excess travel on the gearstick.....I'll investigate further!
Thanks again