About a year ago, I was working on my neighbor's '72 westy. I had the front up and was about to get underneath to work on the shift linkages. I got the van onto stands with the wheels off, and then walked to the front and gave it a hard shove to make sure it was solid.
I heard a "PING", and then it wobbled a bit. I crouched over, and pushed the van as I looked. On one of the stands, two legs would wiggle; the other two stayed in place. I turned around to get the jack, and the whole works came tumbing down.
Here are the pictures I took of the stands:
Now, look at how the horizontal bar is free from the legs of the stand:
A closer look at where the bar broke free. Look at that weld... do you think it had sufficient penetration?
These stands were 2, maybe three months old when they failed. It really scares the hell out of me... how many of us check the weld quality on our jack stands? I never did before, but I can promise you I sure as hell do now!
Be careful out there folks!