Thank you for the instructions, David.

Admittedly, taking apart, then reassembling a zoom lens is not for the faint-hearted.
Those, who have nothing better to do: why not get you one of hose battered of no-name, or both, zoom lenses that can be got for next to nothing? And play with it a bunch of screwdrivers and spanners. Nothing to be lost.

There are certain ‘rare earth’ elements that cannot withstand any rubbing without leaving telltale scratches.
The same time they should easily be polished again with the right with the apt abrasive. Or do I overlook something?