Hi, not sure if the air cooled and BIS are the same but I have a feeling they are? You'll need normal basic tools to remove the hub/stub axel assembly then once out you'll need to strip the whole thing down so you'll need to remove all the drum, shoes and back plate then drive the top bush out. It's most likely you'll destroy it by doing so, so buy another - there not expensive. Once that's out you need to undo the plug at the bottom of the swivel joint. You'll need a funny two pinned spanner or if your lucky tap it round with a punch. Once that's out you can then drive out the old pin from the top. With that out you then need to remove in inner bushes. When you buy a kingpin set it comes with new ones. These have to be pressed in then reamed out to size using a reamer or honing tool. Then press the new pin in and replace everything else in reverse order.
it's a fiddley and time consuming job but strangely satisfying once done. How much play is there? Have you tried pumping fresh grease in? Sometimes that's enough to take a little play out if it's only a small amount.
