Hi everyone...my bolero radio in my 63 plate Yeti has started to act up. 

Intermittently the radio reception is as if we're in a tunnel/bad reception area/passing under power cables.

On checking the setup screen, Ant1 is off and Ant2 is on.

I've removed the unit and checked the connections at the back and they are okay, so I'm assuming that it's the antenna base that's the problem.

Any thoughts on this , or advice about replacing...I'm getting the impression that it's not an easy job!

Did you get a resolution of this problem I have same.

Nope, only solution I think is to replace roof aerial ...but not easy and could be quite expensive, with no guarantee to fix the problem. Tend to use phone and Bluetooth connection instead. Sorry!