Janie,
The Singer site: {
http://www.singerco.com/accessories/instruction-manuals } has the manual you need in a free .pdf download.
I've been told the 600s still have steel gears. I've not had one to look at though.
As for cleaning, I'd not use the Goop on the 301 or the 600. I've had weird things happen to the finish of newer machines with it, and just about ruined a red eye. Generally I use Simple Green sprayed on a rag then wiped on the machine, newer ones only. That seems to work pretty good. Others have suggested Dawn dish washing detergent diluted with water. Older (black) machines get oil and cotton balls.
Joe