Thanks All!
I gave the sponge a WD40 bath and watched the gunk flow out into the WD40. Then put it back in after a wipe down of the Box (both in and out) with WD40 again.
As mentioned, I have a ton of projects I am trying to get through, some are servicing related, some basic maintenance and cleaning, others are electrical additions.
I am documenting and photographing as I go and will post the results under a "Beginners Guide To.." series.
Oh, and just for Juvecu I am going to complete my air pump tests and post in an official 'review'.