iwms (inlet water management system).as you look from the front,remove the left side panel.the iwms is behind there.it gets blocked up and causes all sorts of problems.visually it will look black and mouldy inside the clear tank at the front bottom corner if it is starting to block up.blockages in the air/flow pipes (all pipes connected to the plastic sump) are also something else you would need to check
ck, January 2009