I went for a drive twice today. Everything was fine, but on the way home, I suddenly couldn't shift to third. It felt like I was trying to push the gear lever to third gear, but forgetting to press the clutch. So it made a weird grinding sound. First, second and fourth - no problems. It will shift to third gear with no issues when the car is not moving. It feels normal, but on the move, it will not shift to third. I knew something was about to happen when I shifted to third earlier. There was a reluctance (getting quite rubbery) to get into third gear, but it eventually popped in.
Any thoughts on what went wrong. It could be the gear linkage needs replacing.