rodent nests

[David V. Corbin]

>>> What is this (urine, oils from their fur, some other sort
>>> of bodily excretion) and is there anyway to clean these
>>> systems and try to recover them?

Probably some combination of all of the above! The choice of cleaning
material will depend on the areas / surfaces / materials you are cleaning.
Be sure to do a good job (especially on circuit boards) as this film is
often conductive.   I have chased a number of very strange and subtle
problems with restored machines to some of this type of "gunk" between the
pins of IC's or crossing adjavent lands on a PCB (if there is no solder
mask).

Good Luck!