Over the last 35 years, I have acquired 5 different Kidde extinguishers for various parts of the house and garage. Four of them have gauges that still indicate they are good but one is that "Pindicator" type with no gauge. Two are the old "Fire Away 110" types and, if I am reading the labels correctly, are the oldest as they have a "1984" on one and a "1985" on the other.
When I called, they took down all the information and indicated that all five are covered. I won't throw these away but they will be put in "reserve" as back-up use only.
FYI - about once a year, I take all these extinguishers down, turn them over, and shake them or tap them on the wall to break up and "fluff up" the dry chemicals. I don't know if this will make a difference but not letting this powder to settle into a hard mass makes sense to me.