Those Jet's have a bearing that makes them go. It's a pricey bearing, and has a life expectancy (See the manufacture for details). Keep them greased and never, ever, ever, force grease in, when it's not coming out. If it's not pumping out old grease when you're pumping new grease in,,, it's bypassing the seal and sending it into your cooling system, ie, your heads. I discovered this when I took my Yamaha apart a few years ago. There wasn’t’ much but I had pumped a few times after the main seal failed the first time (I’ve rebuilt my Jet Pump (bearing and seals) twice now. These lower units are amazingly simple and an engineering marvel, but they need care, or they’ll let you down when you need them the most. They take us to places that not many can get to, to offer assistance. So it’s best to be extra nice to them.
