Ibook Dual Usb Fan Problems

[B1smooth]

My G3 ibook is behaving strangely; periodically it prompts me to 
shutdown/sleep/restart without me pressing anything. Sometimes it 
completely shuts off by itself. I have my ibook in pieces currently and 
the fan doesn't spin what so ever. Can anyone with a G3 ibook tell me 
what regularity their fan spins? The fan is near the very top middle off 
the keyboard..below the lcd, behind the little white grate.

Thanks
B1
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