Leaving the drop down flap down for the moment to see if any adverse operation..
so tuned in to 999 The freesat INFo Channel..
Usually it is on plain old 576i but in the mornings it is on 1180

I then found that if i entered Diagnostics with 999 selected..
only ONE tuner was showing.. and lousy characteristicx at that..
Changing over to BBC1 etc i got the usual 90/100 on all the lower dozen or so channels..and TWO tuners showing
Perhaps 999 is used for internal verifications?

Stan

Just tried 999 and diagnostics 100% signal 90% quality both tuners.

Just tried ... 999 was on 1080i until about 0825 then 576.. Internal testing i guess?
and
strangely Graham ..I only got one diagnostic of 60/80 in the pouring rain from 999
and YET 90/100 from both tuners.. in the pouring rain for the first 12 channels..