In general, pump companies did not offer repair manuals. Most companies supplied a parts manual, it was in the create with the pump. This manual was used by the person who was doing a repair. When he discovered which part needed replacing he could get the part number and order the part. Some part manuals even had the cost of the part. I offer a number of part manuals for the 850, mainly because they made different versions of the 850 and also offered parts to convert the old chain drive mechanism to the newer version. These manuals are shown on this page of my website: http://petrolianacollectibles.com/tokheim%20850.htm
Quite often I have asked if the parts manual tells how to reassemble the pump. It does not, but it does show every part of the pump.