It’s not that difficult. Just make sure that you take all the relevant dImensions carefully such as hole centre height and diameter.
If you’re doing just one post it’s a little easier as you have a second one to copy so machine the stub off until it’s flat and then drill and tap a suitable size, I was able to use M4. VERY IMPORTANT- when drilling the body you must ensure that you don’t drill the hole too deep and go through into voids or cavities/passages, the hole must be blind. You may only be able to get a few threads in it but that depends on where the post snapped off.
Finally, fit your drilled and tapped new post with JB Weld to lock it in (don’t over tighten it) and let that harden overnight. I find it’s easier then to either carefully machine or file the flats on the new post which will be at 90deg to the axis of the pin.
If you can post some images of your broken post I can advise further if required. PM me if you need more input.
The two images below are of my carb body before re work. It had a smidgen of corrosion after 35 years being stood in a Barn in the US with fuel left in the carbs!
Regards.
