Phil Fern kindly pointed me to some graphite rods on Aliexpress a few days back, and I got the delivery of '3mm*100mm High Purity Carbon Graphite Rod Bar For Electrodes' the other day and at last have found time to try them out.
THEY WORKSo thanks Phil for that pointer - I made up an electrode simply by using my '3 mm pencil sharpener' and sheering off the rod at the correct length, and blow me down it correctly identified an ingot as LM2 which indeed it is

This now assures a long term supply of electrodes - I bought 26 rods 100 mm long so should last a little while - and confirms Steve's suspecion that they needed to be pure graphite.
I've still not returned to the second (now dead) Analoy 1401, but with the book of words fault finding should be a lot easier.