Where may I obtain an "Operating Instructions Manual" and a manual with a "Parts list and Schematic" for the 1270B. There are several listed on the internet for the 1270 but I can't find one for the 1270B. The Bias Adjustment shown for the 1270 is not complete. What is the procedure for setting the Bias on the 1270B? Is there a service manual for the 1270B?