These video’s shows how to disassemble the lens and clean the oil that leeks on the aperture blades. Then the other video’s who how to reassemble the lens back together and tips how not to damage key components.
WARNING! Do not attempt this without a spanner!!! Please!! Or go ahead, it’s your lens he he!
Some lenses you can get away with no spanner but this particular lens is very difficult to do without the proper tools.
This is video 1 of 3.
This is video 2 of 3.
This is video 3 of 3.