Radio (and TMC) not having great reception

[whiffin]

I have a cabriolet, so I know all of the gubbins are in the boot

I know this is common, and I know usually people say

a) the connector on back of radio
b) the amplifier faulty
c) the aerial faulty ( I believe several in the cabriolet)
d) snapped wire connector as it goes to the boot

I'm taking the boot lid apart tomorrow to check, and assuming that the snapped wire is most likely, but I was just wondering if anyone has any bright ideas re testing the components.

Obviously hard to see a broken coax cable (I'm assuming coax), I'll look for dry joints, try flexing aerial(s) etc, but just wondered if there are any tips or things I should look for.

Thanks