I dampen a new soft paint brush with a small amount of water & brush out the crevices. If you are going to wash the shade, I put an old towel in the bottom of the sink or bathtub & swirl warm water, if it needs more cleaning than that, just use some mild soap & a washcloth. Let the shade dry on a towel.
It's a beautiful lamp..... Good luck to you. Maybe you will decide to keep it. GG