I use the washer and/or a thin piece of plastic or plywood to shim mine on the left side of the mount. I then position the fuselage on its side in a jig position by using a level on the side of the vertical fin, fuse etc. to make sure the c/l of the fuse is maintained and then use my Robart incidence meter which attaches to the prop nut to check for the 2 degrees. A simple way is put in two washers and fly it and if thats not enough adjust from there.