I read the previous replies and had a look underneath mine and found the polystyrene float mentioned etc. However there also seemed to be a small black hose that didn't seem to be attached to anything. All the relevant hoses seemed to be tightly in place and I can't figure out what this one is for. Is it some kind of overflow set to trigger the polystyrene float to cut out?
howtomendit.com for free repair help, information and advice.
