GB3UD Analogue input still active?

[G0NMY]

Well I went up into the cold shack this evening, and had a tunefor gb3ud, at first I couldnt find it. I was thinking its off air, then I noticed the positive to my preamp had become disconnected, and up popped GB3UD
I tried putting an analogue signal in but couldn't access it, so I'm guessing either the analogue input no longer exists or it is in beacon mode.
Here is a pretty D5 picture

cheers Mark