Maybe the float is stuck, you may be able to see the top of the float through the pump cover, give it a poke to see if its stuck up against the micro switch.
StalinDied1953
December 2013
as you look from the front you need to remove the left side panel.at the bottom back corner is a float switch and possibly a pump.if the pump has failed this is the problem but if no pump fitted could be blocked up with fluff or float microswitch needs adjusting