The hydraulic system is the next thing on the list. Changed the oil yesterday, the problem is still there. Its very hard to describe, but it will change gear perfectly if I make the effort not to push the gear lever too far over when going from 1 to 2. The plate was fine, not fractured as I first thought.
Lets hope it is the clutch hydraulics. Regretably, another gearbox within less than two years does not make it financially viable to keep the car, as the engine is now at 205K miles, although still going well, fingers crossed!