Guys, I have a persistent oil leak (gearbox oil). The leak dribbles down the back of the gearbox and drips from the drain plug and all places close to it. It seems to be coming from the region of the speedo cable but I cannot see exactly where it is coming from. It does not leak when the car is stationary - only when it is moving - but leaks enough to drip lots after the car stops.

Does anyone have any experience of where the oil might be coming from? Does the speedo cable connection have a seal which fails?