Depending on how much and where -
1. q-tips dipped in either denatured alcohol or 90% rubbing alcohol or kerosene (lamp oil) and don't get the alcohol on your painted surfaces. (Pour your solvent into a small glass cup to make this easier.)
2. Toothbrush dipped in one of the above and scrub (I usually put paper towels strips around and under to catch any over flow or over spray)
3. strips of old t-shirts dipped in one of the above.
4. If you are talking about grease cups (Singer 201-2 and Singer 15-91), use the flat end of a cheap spoon or fork and dig it out.
5. Tiny cracks and crevices can be reached with a toothpick or a wooden skewer - dip the sharp end into the alcohol and then stick it in a small area of a cotton ball. Twist/wrap between your fingers (it will stick and make a skinny q-tip) and dip in solvent again. The less cotton, the smaller the tip. This will get in tiny spots.
That's about all I know about the subject.
bkay