Get ahold of a Seloc's "Mariner Outboard, 1 and 2 Cylinder, 1977-1989" manual (ya, I know yours is 76 but the 60 Mariner was mechanically identical through it's entire model run).
This site sells hard copies and download copies of Seloc's (have to check to see if they have both for your particular application) or numerous on-line places as well as many local marine places will stock it - also might find a used copy with a bit of looking around.
The hard copies go for about 35 bucks (new) and cover everything from minor maint all the way up to a complete rebuild (including diagrams and charts)...