A140 Dash Air-Flap problems.

[mobi]

I look after an A140 and just recently on turning on the ignition a regular knocking behind the dashboard could be heard for about 20 seconds , it would then stop and may come back for another go.
I think it's a motor trying to set the airflaps, first lifting it then dropping it, my question is , how difficult is it to repair/renew the faulty parts, it looks a right pig to get at.!!
Mobi.