When I got my first FW, I bought a book by David McCallum at
http://www.featherweight221.com which has large detailed illustrations and instructions on FW maintenance and repair, paint and the carry case. I liked it so much I bought the DVD which walks you through the lubrication procedure. It even covers the Singer 301. Someday, I'd like to attend one of his FW workshops.
His illustration for the area under the swing open top thread holder shows two spots that get oil and the upper main shaft gear which gets grease lubricant. There are actually seven areas that I oil from the top. I use sewing machine oil with the zoom spout and Singer grease lubricant.