My series 3 gearbox has a problem, it seems as tho i cant disengage 4 wheeldrive in high ratio, the gearbox is out at the moment as i need to replace an oil seal, and both output shafts turn regardless of what ratio or position the 4WD lever is in, i know that in low ratio 4WD is automatically engaged, but in high ratio 4WD is selectable, the 4WD lever does not seem to go all the way down whilst in high ratio, and i can only get it down, when the high/low ratio lever is some were in the middle and then its locked in postion, meaning 4WD cant be disengaged! Any ideas?? Thanks in advance. Chris.