Well am pleased to report success after replacing the damaged ribbon cable - it’s the cable between the loaders daughter board and the CFS mother board.
To open up the CFS I followed this Replace CFS Mainboard | Creality Wiki
It’s relatively time consuming process with lots of screws and keeping some 6 ribbon cables from getting trapped when reassembling. The ribbon cable was the one that connects here - see red arrow.
The plug is glued onto the socket but a scalpel and a thing flat head screw drive was able to unstick it.
After replacing the cable I took a close up of the damage on the original cable with my digital microscope. I believe this happened when I took the loaders out of the CFS to look for a blockage before this problem arose.
When I reassembled it the ribbon cable got trapped between the loader motor block and the base of the CFS and I tried to screw in the screws and damaged the cable which affected loaders 2 and 3 only. I did not notice this afterwards as I most likely continued to use loader one some time and only later tried to use loaders 2/3 .
Somewhat disturbingly I have 3 screws left over after all this and while it’s working am not inclined to open it up to see where they come from. 
I have to say Creality have done the right thing here. I counted up 18 emails sent over this and Creality generally responded within 24 hours most times. They also sent me over AUD$250 worth of parts to try and solve this problem. This was a tricky problem to resolve, Thanks to all those that Helped.