Dyson DC battery charger repair

[Specmaster]

Does anyone have any idea where I can source a replacement DC barrell power plug to replace the broken one on the charger? It is 7.4mm on the outer dia and 5mm on the inner dia with a centre pin. This one is unusual in as much as its a 3 pole plug where the outer contact of the barrell carries the 0V, the inner wall contact carries 16.75V+ and the centre pin carries 24.35V +.

All the DC barrell plugs I can find anywhere are all 2 pole, the outer barrell contact and the inner pin with the barrell inner wall being plastic, but the Dyson plug has a contact there?