Karcher WD3.300M My machine suck the dirt up until a stage and then I need to blow the pipes out and vacuum again. Please help??? What’s wrong …

\015 WD3.300M My vacuum suck up the dirt but just for a litte while, then I need to blow the pipes out and then it sucks again. When I’m done, some of the dirt falls out of the pipe again. I’ve already changed the vacuum bag and the cartridge filter, but no luck! please help?\015 – Karcher Vacuums