The focus assembly comes off in one piece as above.
Unless this part is faulty in some way DO NOT disassemble it any
further.
Doing so is a tricky operation as it upsets the infinity focus setting
of the focus system which can be a real pain to get right again , so
unless you are familiar with lens repairs do not undo the tiny screws
like the one between the 3.5 and 4 M marks.
The are three screws not to undo , one near the infinity mark and
another one not shown a bit further around.
