SC48 - Help with Noisy Input

[BD123123]

Hi,

We have an SC48 and it sounds like one of our inputs has gone "bad". Input 6 on the top card.
Patching this input to any channel/fader results in "noise". All other inputs are fine.

Can anyone help with understanding what might need replaced? Does the whole card (16 inputs) need replaced or can a specific input be fixed/replaced?
Or how do I go about finding the offending part - e.g. A/D convertor. Are there bits on the card can be swapped to identify the specific component at fault?

Unfortunately we are out of warranty.

I know Avid have a place in Dublin, Ireland. Does anyone know what services are available at that location? Do they do repairs, parts or service?

Thanks for any help.