It has been my experience that if one notices a drop in vacuum during
dry months, it is usually due to the fact that the leather work has
never been done/or correctly done (gaskets, valve facings, etc) and
the wood should be resealed as it becomes porous with age.

Additionally, all screwed together parts that have gaskets must be
screwed together tightly short of stripping the screw holes.

I can't imagine the Seeburg factory offering or suggesting accessories
such as water containers and wet towels.

Stephen K Goodman - Professional Player Piano & Nickelodeon Restoration
Tarpey Village (Fresno/Clovis) California, USA
http://www.mechanicalmusicrestoration.com/