On 26/03/2018 13:06, Harry Bloomfield wrote:
RJH brought next idea :
Couldn't see anything obvious. Some wire looms loose. But it'd take a
lot to create that sound. Another step is as you suggest - fire up
without the cover on - building up to that :-)

You will be OK with just the outer cosmetic, none sealed panels off.
Under that is a second room sealed panelling system, with out which it
should never be run.

The panel is sealed with a gasket - but I wouldn't have thought it's air
tight. Taking that cover off reveals all the components - there is no
second panel (see the pics above).

--
Cheers, Rob