It is not recommended to remove the all eight screws of the lens mount.
Only four screws need to be removed and the mount/spacer assembly can be removed as one piece.
This shot illustrates the ball bearing race for the aperture linkage.
The small ball bearings are easily lost, so use caution if you disassemble the lens in this way.
See the next photo for instructions on which screws to remove for easier dissasembly.