Well I could get the filler plug off no problem, really easy. But the gearbox drain plug which I knew was pretty inaccessible was a no go but so was the diff drain plug - I just couldn't get my 12mm 1/2" drive hex in there or rather I could but I couldn't then get the ratchet on to it. Maybe a smaller hex or allen key would work. Either way I really did it to try to temporarily resolve the jumping out of 4th thing, so will try removing the swarf (sp?) from the casing tonight and see if that makes a difference. Interestingly 4th seems fine after the car is warmed up, I guess the warm gearbox oil helps it.