Does my R75 need a rear screen repair?

[Scarbs]

FM on my radio unit isn't working, TV unit isn't picking up channels (although SATNAV and display work). Both have been water logged in the past! (see relevant posting)

I've noticed, when the demister has been on, that the top three bars do not work on the rear screen. Neither do the two squares opposite!

I'm aware these are the aerials.

What might be the cause of the non-working bars?
How does one repair?
Might the bars not working mean the units are not functioning fully - or is it simply co-incidence both problems are evident?
Might it be the units causing the bars to not work?

Thanks for any help in advance.