Crown CTs8200 switching on/off now and then?

I have x3 Crown CTs8200 and one of them, often switches on/off.
I gather this must be to do with a relay switching to protect the amplifier.
Its not cross-wired each amp drives its own surround speaker.

So question for who knows more about this is what do you reckon/think is causing the amp to switching on/off.

I have pulled the amp cards out for visual inspection that appear fine? It doesn't appear to be overheated and most time the amplifier is running well under the maximum power rating often idle and still now and then switches off then back on again.

So it is an easy repair to maybe replace few certain components I just need to know which ones with some visual pictures so I can see where and what I need to replace.
Thank you.