TRS 80 Model III mini drive problem...

[Degnan Co.]

Looking for diagnosis or URL with troubleshooting guide:
TRS 80 Model III with two mini drives.
Powers up, drives spin and do not stop. 
Does not attempt read, no red drive light.
Cass? and Memory Size? Ok
Basic prompt OK.
Type in and Run basic progam OK
Did not test loading program from tape.
Never opened (until yesterday).

Seeking help.  I have sme experince with basic board work/IC replacem.

Could it be U40 or U41?  "upper" RAM?

Thanks!
Bill
vintagecomputer.net (coming soon)

I have 

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