Where can I find a service manual (with electrical...

Question

I bough a brand new National rice cooker that sit in the store for many year(more than 15 years ?)When I took it home I found out that thing did not work.After by-passing the timer ,That thing still not works.I need a diagram to trace down what was wrong with the cooker(heating element or microswitch?
Thank you very much.
Tom
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