What a crappy discussion. Okay, the calcium can be handled with vinigar treatments. The head
starts out smaller because it is there that the work is done to the waste. Pushing it into a larger hose is easier than trying to push it into a smaller hose. As stated before, paper is the second worse offender. The first, and assured to jam ANY head
is the dreded tampon. Also an ashtray full of buts is also non-passable for the grinder blades. Trust me on that one, I have had to pull and clear the heads on my boats because of two daughters, granddaughters and a wife who, early on, was sure I was the one jamming the head up even though I showed her the tampons and cigarette buts. I don't smoke, the wife and all of the daughters do.
Vinigar for the calcium buildup. It really does help.