I noticed some brown fluid beginning to drain from my mixer a few months ago, so I decided to spend a couple hours changing the grease on my KA Pro 5 Plus. It’s not difficult but it is tedious and you’ll go through plenty of paper towels and Q-tips.
You will definitely need a small container of food-grade grease. I’d recommend replacing the gasket, although I did not. Tools I used: a couple of screwdrivers. There is a small metal snap ring that is tricky to remove and replace without snap ring pliers ($5 at Ace Hardware, highly recommended). And a hammer or rubber mallet.
I used this YouTube video https://youtu.be/HxdQnF5AgUk which was quite helpful. They make videos for other models so make sure you’re watching the correct video!
You might find that you have a gear that needs replacing. Mine were fine. So prepare yourself for that eventuality, and remember that replacement parts are easy to find.