Behind the cartridges The unit was removed and cleaned.
Yes I think so I cannot see the full view properly. I took out the cartridges then lifted a lever and the unit came out.
It was cleaned by my son in law with tissue to start with and then I believe he washed it because he told me to leave it 24hours to dry thoroughly. I have never replaced anything on it before. I have had it probably about 10years or more.