My WMA36 had the same problem. You need to loosen the large hoseclip which holds the Filter housing onto the bottom of the drum casing and pull/twist this housing down untill it comes off, inside of this housing is a removeable filter which is in 2 parts (top and bottom cages) and inside this there is a ball float.
My unit had about a 1/2 Kilo of crud jammed inside, this prevented the water from reaching the pump. Clean it out and reassemble - it will now work - Guaranteed!! (I wish Hotpoint would put the filter in the front of the machine with an access hole there, it would make cleaning SO much easier!!)
Martin
February 2010