According to the manual check the following, discharge hose is not bent. Filters are not blocked. Syphon is not blocked. You can download a manual from Hoovers website by pasting the following link into your browser. http://service.hoover.co.uk/manuals/Manuals.aspx?Section=3
Alan
December 2007
I can answer this question...
Hoover DT999 stopping half way through cycle flashing E4?