Mechanics and Fixing Any Questions Answered

Also, how do you adjust the pre-load on the bearings if the stem is that stiff on the steerer?

Once it's seized on you'll struggle, but if you take it off, clean and grease it then it should be fine. Just give it a pull and wiggle, it's exactly what the shop are going to do. I was going to suggest loosening the bung but those specialized ones are a bit odd and will stay put unless you know how to remove them, although maybe backing it off a little will help, just don't do it too much and lose the nut down the steerer.