I remember seeing a small spot of phosphor knocked off a monochrome CRT in an early-to-mid-'60s Zenith table model. (Please don't call it a portable; it makes my groin ache like the very dickens.) The void was about the size of the head of a sewing pin, but oblate to a ratio of about 5:3--vertical to horizontal dimensions, and off the center axis by an inch or so to about a 10 o'clock position. There were rambunctious kids in the house where this set resided, and I tried to imagine perhaps a metal toy car (like those "Hot Wheels" of the time) thrown against the screen--not hard enough to crack or chip the glass, but perhaps hard enough to disrupt a tiny spot of phosphor....
Also I have seen the bonded faceplate discolor, crack and craze around the perimeter of a number of color sets. I have a Zenith console up in the hayloft here that somehow managed to escape the disposal campaign my girlfriend started me doing back about 12 years ago--IIRC. I threw away about 50 large console color sets, and about a hundred table models and portables--color and b&w. All in various states of completion and repair. All accumulated over the years. All repairable, but with no market at the time--working or no, and no time on my part to fiddle with them even in fun. There were a number of the color ones that were afflicted with this sort of glass leprosy. I suppose the integral implosion protection is still for the most part there, but it still looks pretty scary just the same.