In order to find the part number for the relays, and also as a contingency, I bought a used CEM from eBay.
So for anyone else trying to find this information:
The relays are labelled as Tyco
V23134-J52-X455
They are referred to as
1-1414610-0
Unfortunately they are not easy to find available to purchase;
https://www.te.com/global-en/product-1-1414610-0.html
Arrow in the US sell 'em in multiples of 5 (plus international shipping);
https://www.arrow.com/en/products/v2...e-connectivity
Arrow in Europe sell them in quantities of 294!!;
https://www.arrow.com/en/products/1-...e-connectivity
I have emailed TTI and Mouser to see if I can buy from them…
Craig.