With the camstack removed you can clean the gears under it a whole lot easier. You can see the stitch selector parts a lot easier, too. The one I was working on had a LOT of grease - on one hand a lot of grease is good - you sure won't find rust. But, the grease can get old and gunky as this one did - I got as much of it as I could and put some Tr-flow grease on it. They do NOT need a lot of grease - I don't know why some OSMGs put so much grease on some of them. A small amount of grease is just fine. Too much and the grease flings all over the place then collects lint, etc. In this case it kept the machine from turning right. I will say, I would rather have one that has been cleaned of grease than one that was bone dry and rusted - once the grease is cleaned off it will move very freely. With rust it is much harder to get it to move freely again. I do know there are folks on here who have that know how.