DO NOT use WD-40 - it's made of fish oil and will eventually become gummy and sticky. Silicone oil only and only on the parts that slide together as Don said.
Gary
wow!!

..live & learn

.... I use WD40 for everything now I'll rethink,....lol...good to know thanx Gary...
Garry is right, WD40 is not a lubricant at all... It has other uses tough... As a lubricant silicone oil will do nicely..