All your emails were in my junk box, filtered by McAfee as spam. I just found them, sorry. I fixed the problem about 1 hour after sending my question. For your info......
The Canon printer has 3 contactors for the FX 10 cartridge. Looking into the printer they are on the left side, Two are "bent wires" and the third is a domed disk, all spring loaded. Non appeared to be faulty, but obviously were not making contact. Gentle bending restored connections. If I had been brave enough to try it earlier I would not have needed your help which would have helped.
I do have a copy of the full Canon maintenance manual (2006 version)and this is not actually mentioned anywhere.