I soak stuff like you are talking about in some diesel fuel and then clean a little with a brush or q-tip using the diesel fuel it has been soaking in, then blow it out with air.
It works and you can buy a gallon for about $3.25 at you favorite Fill up location (CA price right now).
Of course farm prices are less, but I doubt you have diesel or you would not be asking
Around a farm it is a must for all the cleaning of bearing's and various things that move better with grease. I use a good set of hand gloves to keep it off the body.
Heck of a weed killer, fire starter,etc. but the enviromentalist's will give you hell.
HQ