Once I got the boiler back in the frames with all the steam fitting attached, the cause of the original water leakes became apparent. I had suspected that there was water passing the gasket between the wet header and boiler, this indeed proved to be the main source of the problems together with a few others. See below for the current to do list.
I have made new gaskets for the wet header, topfeeds and dome, however there was still water passing the wet header bush. On closer inspection it was apparent that the thread was in a particularly poor condition, I decided that it would be beneficial to remake this bush instead of attempting to make the existing bush watertight. The next pic is of the new bush partway through machining on my dad's Colchester Student.
Here is a closer view of the new part machined bushed alongside the old bush.
This is the current position of the new bush, still required is for the centre of the bush to be drilled, followed by internal and external threads to be machined, parted off and superheater location holes drilled and tapped.
The final pic is more for interest and shows my own Myford Super 7 back to back with the Colchester Student. This is lathe on which the vast majority of my machining takes place, however due to the size of the piece of bronze used for the bush I decided to graduate to the Student!
I hope to have my next stint in the workshop this coming weekend and fingers crossed I should be able to provide an update soon after. Once the bush is complete the next task is to check the packing in the LHS cylinder and then (all being well), reassembly in preparation for the next hydraulic test.