iPod hifi fails to recognize iPods

The iPod hifi seems to work, the light comes on as usual when connected to power, and reacts properly to remote control signals.

However, it doesn't recognize when an iPod has been plugged in. I tried this with multiple iPods. It literally just stopped working from one day to the next. I checked the connector, and to the eye it doesn't seem damaged.

Anyone come across this?

I'm dreading bringing it in for servicing just to have them quote me a $ 400 repair, and then suggesting, with barely a pause, I should just buy something new instead.