Iím not aware anybody has detailed and photographed the process of stripping that down.
I know we have one or two in the workshop that need it doing from time to time. It doesnít seem to take very long or cause any problems, so it canít be terribly complex. They are usually only a spring and a seal that gets muck trapped in them.
Removing the HEPA filter is something that is covered in several topics here. Search CRU, I seem to recall some guy used that term and put quite a detailed explanation.