I had trouble with the grease they used in my nrs pump. It became very tough to pump after pretty modest use 12+ years ago. The thick grease seemed a magnet for any grit, sand or silt,etc.
After the first season, I wiped it all out and sprayed 303 into it.
Never abit of trouble since and allot less maintenance.
Still works like it you'd expect it to after all these years, too.