PU means there is a problem with the pump. You can remove the pump which is situated at the back towards right hand lower corner (right hand as you look at it from the back) its not that hard to remove. You will need a pair of pliers to remove clamp and a couple of screwdrivers and maybe a small spanner. Sometimes the pump is just blocked. Clear it and try, if no luck a new pump is required.
Mary Sotheran, May 2010
