I would not soak it for fear of getting grime in the passages and later in the bearings. IMO , I would get some heavy duty duct tape and tape off all areas in that will let grease and grime into the internals. Use simple green or that purple cleaner, purple might work better for you since it more stronger and will even soften the paint. You will need about 3 different size d brushes to get all the areas. Harbor freight has cheap brushes.