Thanks for the guide and the photos. It took me just a few minutes.
Am I correct to think that the butterfly stays in place?
None of the steps seem to instruct on how to actually remove the butterly from the air Intake
and when I looked at it - it seemed rather firmly mounted in there.
By the way - for sealing the end of the hose I found a 4mm "repair plug" for garden sprinkler hoses fitted just perfect.