I have an issue with my 1993 case international 844xl. Apart from the engine it is very like the 956XL. First of all could some one explain how the rocker switch for the 4WD works on the dash. Is it Hydraulic or electrical. If the switch is engaged and the front wheels do not turn what could be the problem. The drive shaft which is in the centre seems to turn even when the switch for the 4wd is turned off.