Originally Posted by J Miller

I looked up that model and it is similar in shape to our 4622A. To pull the top off that one you have to first remove the nose piece, one screw down towards the bottom, then under the left end of the top you have to loosen a screw that holds a sheet metal part that's attached to the underside of the top.
Then there is one screw through the top at the left end, and two screws through the top at the right end.
After that you have to remove the knob from the stitch length lever and then wriggle the top off.

Now, since you can't figure it out yours might not have the screws on the top. The few pics of that model I found are so small I couldn't see what I was looking at.
Could you post a couple close ups of the top and front?

I can tell you that the internal parts are stamped sheet metal and plastic. There isn't much to lube on the sheet metal, but the plastic "might" have been greased in the past. I had to clean the old grease off the gears in our machine because it had become stiff and gummy. Tri-Flow grease did wonders after that.
The shafts are steel and pass through bushings in the aluminum body. T/F helps there too.
And under the nose piece there are many moving ZZ mechanisms you can't see well, but if you can get the T/F oil to them you'll think you just got a new machine.

Will try to find better pix and or manuals.

Joe