Are the beans fresh? Can you choke the machine with the beans and your grinder? If you can choke it then back the grind off slightly.. If beans are old, get some fresh ones.
I'd start off with weighing your beans to take the dose out of the equation.. Then grind finer, if no help, try fresh beans.. Check your grinder then your machine.
How long is your pour?
Not sure where your at but if your in Adelaide then I'd be happy to compare my machine to yours..