Age-old Question Again - Cabling Advice Needed

I bet you are probably sick of being asked this question but here you
go...

I receive DTT from Belmont which uses Ch 30 up to 68 and also Ch 22
for analogue. As a result, I have a wideband aerial fitted outside.
Originally we had a Group A aerial in the loft space which worked fine
for BBC1, BBC2, ITV and C4 but not C5 (which is on Ch 56 or somewhere
around there).

At the time the wideband was put up (outside) we had a direct line of
sight to the steel works and hence the aerial was put behind the gable
to reduce ghosting (but still has line of sight to the transmitter).
The fitters put in a Labgear MSA101 boosted distributor to bring up
the signal strength.

Since then they've built up between us and the steel works and
ghosting has gone altogether. Would it be worth raising the aerial?

In 2001 we converted the attic space and put in an additional TV
socket. Around this time we noticed dots of interference on ITV and
C4 analogue. More recently on Freeview it shows itself as frequent
breakup. We used the generic brown coax the electrician left which I
suspect to be the problem (and it is used everywhere else too)

It has got to the point where it is really annoying so I am
considering replacing this cable run with CT100. Is it likely that
the majority of interference is being picked up by this section of the
cabling - i.e. can it travel back into the Labgear booster onto the
other output? I'm pretty certain it started when we converted the
attic, but maybe it's just a coincidence that all the kids grew up and
started using over-revved lawnmowers as their primary transportation.

Replacing the cabling to this run is easy as the cables are exposed in
the craw space, but it will be a pain to replace the downstairs cables
which are embedded in the blockwork.

I've already ordered some CT100 based flyleads for use around the
computer (where I have a PCI Freeview card).

Thanks in advance for any advice and apologies for asking a common
question.