The Sony LBT-V202

I bought this Sony Compact stereo system around Christmas 2020 and until today it has been languishing in it's package, unopened, waiting for me to make the time to 'sort it out'!
Well today was the day as it was raining and I couldn't do my planned work outside.
Firstly there is the slight mystery of why it's accompanying record deck was already out of the (sealed) box ? but I guess I must have bought it separately though I didn't think my memory was that bad, maybe it's just about the large number of stereos I seem to have bought recently.
Anyways, straight out of the box all was looking fine, a quick inspection of the front panel showed that everything was present and correct i.e. nothing missing or broken.
In particular the twin cassette decks looked immaculate although I wasn't crazy enough to think they actually still worked, as (in common with most of my purchases) it was specified as 'spares or repair' and as usual it was the tapes that didn't work !
But to my dismay when I plugged in and switched on, the function switch refused to operate and one of the tuner presets was pushed in and would not budge ! also the volume control knob was very stiff and would not turn at all using the remote control.
However, all was not lost as I've had this sort of issue before so with great care I dismantled the unit and removed the front panel and proceeded to extract the main PCB which was behind the problem switches .
The volume knob put up great resistance to removal but was eventually 'levered' off with a small screwdriver.
A general 'going through' of the switch assemblies ensured that everything was back to normal which led to reassembly and testing.
OK I know that the tape decks are still inoperable but I've had a 'butchers' and I think they are fixable, (just not right now) and also I believe that they use the same mechanisms as my recent LBT-D101 so I may fix them both at the same time.
The speakers are in good working order but the nylon stocking material is ripped in many places and so
needs replacing as soon as I can work out how to do it.
In summary, although still a work in progress I have high confidence that I can fix this one and make a good return on the 99p (plus £6 p&p) that I paid for it !

[@Tidwillshare]

Do you know what the SAT knob is for? I was recently gifted one of these stereos and I have been looking everywhere for an explanation of that function, but no luck.