Your 'fatty globs' could be fungus introduced from the wood.
I think it is impossible to clean all the crevices in the MiniMill base which holds the coolant and the lines leading up to the spindle so I think you are going to have to use a powerful disinfectant and fungicide. Concentrated bleach would do it but that is a bit dicey because if it gets into places where it doesn't get washed out then you have a potential corrosion problem. In a similar situation but nowhere near as bad I used an old fashioned coal tar disinfectant called Creolin that is, or was, used for washing out horse and cattle barns; stinks horribly and irritates your throat but dissipates over a few days.
An open mind is a virtue...so long as all the common sense has not leaked out.