Rob, a question can't be stupid if you need the answer and you read the replies carefully. It is a fairly regular event here for people to lose that needle when assembling the carburetor, or to install it upside down. You described the problem so clearly that the most likely explanation was obvious to anyone who had dealt with it before, but not to someone who hadn't.
Please let us know when you get the mower running well, or post further questions if you have more issues. I think you will be rather happy with the machine - I'm a 4-stroke person myself, but the Victa made 2-strokes extremely popular in Australia, and I think you'll see why when you start using it. When working properly it is easy to start, powerful, and reliable, as well as quite uncomplicated when maintenance is required (except for the carburetor, anyway).
