I have a 14" JET bandsaw (JWBS-14CS) that has performed well under light use for several years. This morning I tensioned the blade up and found the tracking a bit off; adjusted that and when I started the saw there was a loud BANG, followed by the sound of the rattling metal. Oh-- and the upper door blew open as well. I quickly hit the switch, thinking the blade had broken. Turns out it was much worse-- the triangular part of the cast shaft hinge that the tracking adjustment bolt presses against sheared off! This caused the upper wheel to slap over into the housing and the blade to fall off. Luckily there was no further damage to the saw (or myself).
I was pretty surprised that this casting failed. From the jagged edge it looks like it may have been cracked for a while (no way to see that, as it would have been on the inside edge) and just decided to give way today after I tensioned up a 5/8" blade. JET doesn't sell just this casting, so I had to order the entire sliding bracket assembly for $40 to replace it.
If you're using a 14" JET you may want to take a look at this casting just to make sure yours isn't set to fail also.