Hello Ian,
I found with google a discussion: My brother's Gutbrod 2060. Did you write it? I just bought similar nazitractor

I noticed you had some problems with it. I have exactly same problem with mine. It won't run with both cylinders. Did you find any solutions for that? Was it carburetor problem or something else? I don't want to open my cylinders without good reason because of main gasket. I would be very grateful if you can help me. You can also write straight to my email:
harri.hassinen@ebaana.net
Thanks,
Harri from Finland