Have sysmon and fan package installed for few years. I fully dismantled, cleaned all plug connections on board with Servisol and re-assembled. Powered up before putting back into set up and fan was running. Connected back into TV and red rain (and other colours) was still there. However left on for a few hours and problem had again disappeared. Sysmon shows fan not running (presuming fan package has fan running constantly - I've set it at 100%). I'll source a new fan.