Eating humble pie
My thanks to Sugeng of Indonesia for serving me up a large and tasty slice of humble pie.
Sugeng contacted me to purchase a PDF copy of The Website Manager's Handbook and pointed out that - contrary to all my endless advice about checking for broken links - I had quite a few broken links on my site!
Outraged at this suggestion, I was sure he was wrong. But no, just as he said, all the links to my downloads were broken.
What I think happened is that during a content update, I accidentally overwrote all existing files with a site copy that did not include PDFs.
So, a lesson ... keep checking your goddamn links (preferably using an automated tool), cause chances are they will break from time to time.
Addendum: Sugeng got his book for free :/