I have an AG100, bought new here in Venezuela in 1980, but considered in the US to be a \´79 model. It\´s a code 497 (first three numbers of serial). It was the last of the first series, the next year everything was changed. Getting a manual for such a rare model is going to be difficult. Most of these bikes were (and still are) sold in Australia. (Therefrom the AG- in the name) I would suggest contacting a dealer or someone connected with bike repair there. Good luck. 
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