Believe it or not, amongst us piano tuner/technicians the
preferred method for tightening loose tuning pins is thin CA glue
(no accelerator).  Techs have been using it for years so it has a
proven track record.  If you don't believe me check the pianotech
archives.  The archive search site is sometimes skittish so search
via Google:  CA glue site:ptg.org

It is the perfect solution to this problem where oversized pin
replacements is not viable.  The beauty of it is that it takes affect
in a few minutes and lasts -- so far, indefinitely -- without adverse
affects to tuning technique or removing the pin and installing an
oversized pin down the line.  It even works after the other 'Pin-Tite'
products have failed.

Regards,

Jon Page