Pussycat , hello and welcome to our Community. Glad to have you and hope you become a neighbor.
Have you inspected your entire unit yet? I mean , read all the instructions , put an 'eyeball' , on each part and played with the moveable stuff ? A good starting point !
Now, after your cursory inspection , fire it up and check it out (apparently , you have ) . so , now I ask , is there a 'needle valve ' in-line with your supply hose , and is the orifice to the burner clean?
If these checks do not help and other 'Duo' owners suggestions are 'nil' , give the MFG. a call and complain , management usually complies and corrects or in some cases sends a new part.
Hang tight and help will arrive . . .