Although I always check the alignment of my scroll saw, spindle sander, and vertical belt sander, it never occurred to me to check out the drill press. Since I never had any problems, the last time I checked for square was when we assembled the tool, about a year and a half ago. It was fine right out of the box.
The other day I needed to drill a deep 1/8" hole for the brass pivot rod of a box whose sides were 5/16" wide. A serious misalignment of the bit could result in its coming through the wall of the box, or at the very least, the pivot rod going in crooked. I chucked the bit into the drill press, and turned it on to see if it was inserted properly. Something didn't look right.
I re-chucked it, turned on the tool, and it still didn't look right. So I put my most accurate square (a 6" Starrett combination square, worth every dollar of its outrageous price) next to the blade, and was it ever off! When I checked the square against a larger bit, the discrepancy was even more pronounced. So, I took out the hex wrench that came with the tool (don't ask how I even remembered where I had stored it), found that the bolt had loosened up over time, and readjusted the table to level in the side-to-side position.
I've taken to aligning my tools by using my eye and the combination square, and find that it's quick and amazingly accurate. The picture shows my setup, as well as the monster wrench that was used for the adjustment. I also checked the front to back alignment, and found that it was still fine.
And yes, had I not checked, I would have ruined a box in which I had invested a lot of time, as well as some newly resawn exotic wood.