It's actually quite easy. The macerator is installed in the top of the holding tank. There are a half dozen or so slotted screws and the electrical connection is via a small bus on top of the tank. Remove it and re-install in the reverse manner. To save your nose fill it with fresh water and pump it dry first. If you don't have access to a pump station you can pump it out with a shop vac. Just remember to throw out the filter after, it will reek. There is a neoprene style gasket between the pump and the tank which you should replace as it's over ten years old. One of the easier jobs I've done.
