How to Move the Central Admin Site, Even if You Already Screwed it Up

Revised! And also see http://bobklass.blogspot.com/2008/07/moving-central-admin-again.html
Moving the Central Admin site the right way is easy:

Run config wiz on old, removing
Run config wiz on new adding


But what if you did something to screw that up, like:

Start Central Admin on new server (through Central Admin)
Stop Central Admin on old server (through Central Admin)
Run Configuration Wizard on new server

which would leave you with NO Central Admin server?

You will have to try a little harder if you really want to screw things up. To fix it:

Run Config Wizard on new and REMOVE central admin
Run Config Wizard on the old and remove central admin
Run Config Wizard on new and ADD central admin

Similarly, you probably could redo the old Central Admin if it were screwed up and then do it the right way once everything was back the way it should have been. The right way:

Run config wiz on old, removing
Run config wiz on new adding

That's all fine, but sometimes SharePoint just won't do things the right way. My production server didn't present the option to remove the Central Admin site (why?) until I removed it from the farm and added it back (and the first time I ran the Config Wizard it took over an hour!).

But then it looked like the "right way" wasn't working. Upon close inspection, everything seemed to be where it should be. The problem was that the alternative access mapping for Central Admin needed to be changed (it still showed the old server). So just put in an explicit address and include ../default.aspx and navigate to the maintenance page, or just use ../_admin/AlternateUrlCollections.aspx and then change it to your new Central Admin server.