But in many cases, such breakable parts are put in place for a reason. They are called "mechanical fuses" - also known by a few other names:
They are designed to break if the machine comes under too much stress that could break more expensive parts of the machine if the "fuse" wasn't included. Instead, that part breaks, making it cheap and easy to replace.
Indeed, if you ever find a Kitchen Aid stand mixer in the trash, it likely got there because a gear in the gearbox is designed for this reason; they are cheap and easy to replace for anyone with a modest amount of mechanical ability, and those mixers aren't inexpensive new.
Is it golden brown, or an off-white?
My mixer is 50 years old. Over the years, I've pulled the head apart a couple of times when it starts to squeak, and it's obvious there is a very gradual loss of grease - I've re-spread it into the gears.
There is no seal on the shaft that holds the beater.
Kitchenaid is made by Hobart, and they are the lead manufacturer in this market. The design is fine and very rugged.
I don't want use any grease that has traces of heavy metals or, e.g., moly disulfide. There is such a thing as food grade grease for use in mixers, candy machines, etc., but I just haven't yet laid my hands on any.