A vacuum cleaner with the brush attachement is useful or even a paintbrush and vacuum cleaner nozzle for cleaning out the dust etc inside the vents.
As for the repair of the flaps, this stuff works well :
https://www.ebay.co.uk/itm/MILLIPUT-...D/390942475261
Get the black stuff, roll and shape it like Plasticine and push and mould it in place to recreate the "welded rivets". You can also wet your finger or a lolly stick, McDonalds coffee stirring stick or similar to smooth the surface and shape it nicely if you need to. I've used it successfully to recreate the plastic around the mounting holes on the underdash trim on mine and several other things.
If you do get some, have a look at the manufacturers website too, loads more tips and tricks for using it.
It sets rock hard, is very strong, can be drilled etc - i call it "Plasticine for Grown-ups" as it's as easy to use as Plasticine but sets like like what a grown-up wnts it to do.
