I retired my gauge (outer tube and all) after it had been out for about a decade, from shortly after the great Reno flood to a few years ago, and replaced it with a new one. Just looking at it, you would think that would crumble in your hand from the intense crazing, but I guess the destruction was only skin deep as the outer tube had considerable remaining strength. The bottom was just cracked enough to permit water to leak out. The bracket, however, was in danger of crumbling and allowing the tube to fall off the post.
I also bought a second outer tube to make a soil percolation/field capacity test column. I've re-used the old funnel and inner tube for the tests.