Thanks for the replies guys.

I did the diode test on the coax socket in the wall - one way gave a
zero reading and the other way a positive value.

I also confirmed I was getting DC voltage on the cable coming from the
set top box.

The LNB setup menu still said no satellite signal.

I know for a fact that the dish was secured to a fixed position by a
workman when he noticed it was swinging about just after moving in. I
guess there is a very high chance that the dish is no longer pointing
in the right direction.

Where would I go from here? I've heard about dish meters that help you
align the dish, but is it something that someone with moderate DIY
skills can do?