I got service manuals & other manuals here at this site (see link), I believe (but I forget exactly where):
http://www.manualsoncd.com/Dir-dirbrowse-2.htm
What to use to clean varies, but here's mine:
WD40 to dissolve old oils b/c it's close to kerosene in composition
Tuff Stuff in a spray can w/ yellow lid. About $3 or $3.50 /can at Dollar General, auto parts, etc.
sewing machine oil to oil but I do also use TriFlo on the machines that are keepers
I used white lithium grease or red grease from the auto parts store on the 401/404/402/500/503 and the 15-91 and 201 potted motor worm gears. Price is right. You can also use Vaseline in place of the Singer grease, I have been told.
WD40 and white lithuim grease seem to have fallen outta favor w/ the sew machine crowd. They were hawt back in 1998-2000 so that's what I have on hand here.