David thanks for the kick.
Job done. Nothing to write home to granny about, but it works.
Polythene along the bottom of the plug to keep the epoxy from bonding.
A cut off pen top that fits in the connector. Soldered up + and - to two pins.
Fitted the pins to the plug, heat-shrunk. Used Araldite "metal" (rapid set) as the epoxy - metal does not mean conducting, just it can be shaped, drilled later.
A cocktail stick pushed the epoxy into the gaps. Waited 10 mins and gingerly tried to withdraw the pen top. Results are "OK".
Keeps me moving.
Sure, the use of the pen-top means I have no keyways to prevent errors, but it allows me to get on an examine the rsr232 comms signals.
See photos for the job and the results