I have tried bead blasting an ic motor that was very stained and had a lot of baked on oil, this came about after reading in an Australian rc magazine (a few years ago) about cleaning ic motors with a bead blaster, the idea was to use very fine beads ie baking powder/soda as this was found to be perfect for the soft alloy of ic motors. i made a gun out of an air duster and added a pick up line like an in an atomiser and put this line in the soda it was very simple but the results were really good, 10min work to make an os91vrdf look new and the finnish was very similar to brand new. Greg