Bravenet (Western NY AOMC) has a lot of resources; mostly parts manuals though. They can be downloaded page by page and then you can make a PDF should you want to. Makes it easier for sure.
I did find this source for a downloadable PDF Service Manual (475 Pages Long!) for vintage Mercury :
http://mercury-vintage.marineserviceman … .html#1953
They charge $5.00; it’s legit with decent quality scans . They list model after model; they are all the same manual. Just download one and you have them all.
Chuck