Legendre, thanks for the offer, I'll probably take you up on it. The only scraps I could find to make the key out of were steel, so I'm kind of nervous about this one breaking off and getting in the crankcase.
I see you've already fielded at least two questions today about leaking Gurtner carbs-- well, after re-assembling mine, guess what? Gas was pouring out around the main jet. I'll try the teflon tape solution, although you can't wrap it around a threaded part.... the only threads are _above_ the jet's inlet holes. Strange design.