Thanks for sharing the info on your seat post problem. This does point to the need for an occasional disassembly of the bike (particularly with a steel frame), looking for frame corrosion, bearing issues, good chance to lube cables, touch up paint, etc.

I recently disassembled a BB on a bike and found it to be two loose ball bearings short on one side. As I know this bottom bracket had not been touched in 25 years, I knew it was due to mechanic error (it surely did not vaporize). The mechanic in that case was me. I guess back then I couldn't count.... I might have noticed the deficiency if I had ridden the bike in the last 25 years (but I had not).

There is no excuse for not lubing seat posts and handlebar stems routinely. They are so easy to do.