One time machine will drain next time won't

It is a common fault that the drain fails to work inmost machines in a period of time and is the most problematic fault in awashing machine.This can be a possible failure within the controller unit as it fails to give output to the drain pump. In all occasions it is important that your observation is mostimportant and so is vital to the identification /rectification and solution. Ifyou have noticed that water has leaked then as the drain hose pump/valve andfittings are located on the underside of the machine it is important that youlook for possible leaks here. In some cases the drain hose would be clogged atthe drain end to outlet of the house and so there will be back flushingresulting in overflow to the outside. Also the drain pump/valve can be clogged.Now remove the drain hose clamps and remove the drain pump/valve, clean thedrain pump/valve, use back flushing to clear off all dirt. Now test using powerto see if this works and can be simulated. When refitting, the hose must be tightenedproperly. If the pump/valve does not work even with power then it must bereplaced. If there is intermittent powerto the drain valve/pump then the program controller unit is a suspect.Cleaning a pump: http://www.youtube.com/watch?v=zKjKi50YBpI&NR=1&feature=fvwp Finally the washer must be placed with a tilt- use aspirit level- so that all water will drain to the outlet port and thereby thereis no residual water remaining. Replacing the pump on a Bosch machine, please checkthis link for tips:http://www.espares.co.uk/advice/washing-machines/a/7/1373/how-to-replace-the-pump-on-a-washing-machine-.html