I tend to let DOF be my friend, and set focus with a guess of about 1/3 of dof in front of the estimated distance, and 2/3 behind it. I have an Ansco cousin to the isolette, and the DOF is indicated on a little dial on the top left side of the camera body.

You have cleared the green once grease, now goo from the focussing and rangefinder? My RF takes a while to spring back, so I guess I have not got all of the green crud out of it yet.