I figured out how to set up the decoder, typed in the code with and without a space before the AM, but nothing worked: I always got an error message. Why is this not working?

Did you put in the numbers at the top? There's a seperate section about the typewriter bit where you put in the digits (rather than type them out).

Sorry if you have already done this, but this is what caught me out for a while the first time I played it.

I started by putting in 8754

Turn on machine to decode after connecting wires to power it. Enter 8754. enter all letters without space. Press decode button

I had an issue too, but I realized I was reading the Decoder wrong (10 year old me figured this out no problem...). I had the number dials facing the correct numbers up instead of in the little black box. Worked fine once I figured out what I did wrong.

Thanks! This is what helped me Advance the Stage! (I was too Stupid to figure THAT Part out! LOL)

In fact, I have to use a Walkthrough just to play the game! You'd think with me being an Old-Schooler who saw the Invention of the Internet that I would know these things! LOL (Yeah, no, I really WAS there before the Internet!) 8D