Well, I contacted Melling USA, after getting no response from Melling UK.
They flat out denied to even know what a pump from a TD5 was - despite it having a Melling sticker on it.
I now believe that someone else has bought that part of their business but I don’t know who. It makes finding spare parts quite tricky.
Despite this, I have managed to recondition my pump with a new bearing, oil seals, gasket and O rings. I haven’t fitted it yet but it feels nice and tight.
If it works then we may be able to recondition our OEM pumps without having to buy dodgy Chinese/Indian ones.